Privileged Planet: Keppler searches for other Earths (Introduction)
by David Turell 
, Saturday, February 05, 2011, 18:14 (4828 days ago)
Is there just one Earth in the universe? Or are there many? Why hasn't SETI worked? It takes many special parts to make an Earth: for example a solar system with iron and nickel; large planets like Jupiter and Saturn; A correct-sized moon to stabilize the planet. The list is actually enormous. But there are many stars with solar systems. At an average 100 billion stars in 100 billion galaxies, surely more than one planet got it right. Well, maybe. Current discoveries in our galaxy:-http://www.nature.com/news/2011/110202/pdf/470024a.pdf
Privileged Planet: Keppler searches for other Earths
by xeno6696 , Sonoran Desert, Sunday, February 06, 2011, 01:34 (4828 days ago) @ David Turell
Is there just one Earth in the universe? Or are there many? Why hasn't SETI worked? It takes many special parts to make an Earth: for example a solar system with iron and nickel; large planets like Jupiter and Saturn; A correct-sized moon to stabilize the planet. The list is actually enormous. But there are many stars with solar systems. At an average 100 billion stars in 100 billion galaxies, surely more than one planet got it right. Well, maybe. Current discoveries in our galaxy: > > http://www.nature.com/news/2011/110202/pdf/470024a.pdf-You're right. The observable universe is 15,000,000,000 years old, and we've only been looking for 2. Time to call the search off, we're absolutely unique!-http://kepler.nasa.gov/ <--daily updates.
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\"Why is it, Master, that ascetics fight with ascetics?\"
\"It is, brahmin, because of attachment to views, adherence to views, fixation on views, addiction to views, obsession with views, holding firmly to views that ascetics fight with ascetics.\"
Privileged Planet: New book
by David Turell , Saturday, December 31, 2011, 19:24 (4499 days ago) @ xeno6696
John Gribbin has written some fine books on science. I've met him in his books many years ago, and he is fine at condensing and explaining. He has now written a book that compliments the ones I am aware of about the uniqueness of our Earth. I've read Rare Earth, which is very comprehensive about the Earth's attributes. Priveleged Planet takes a more Godly view and points out that our position 2/3rds out the second arm puts us in a thin area where we can make cosmologic discoveries easily.
http://online.wsj.com/article/SB10001424052970204552304577116570107579152.html?KEYWORDS...
Privileged Planet: New book
by David Turell , Thursday, March 05, 2015, 05:23 (3340 days ago) @ David Turell
The belts that protect us from attack, by blocking killer electrons but let in the right type of radiation to support life:- http://www.evolutionnews.org/2015/03/how_space_shiel094051.html-"As the first significant discovery of the space age, the Van Allen radiation belts were detected in 1958 by Professor James Van Allen and his team at the University of Iowa and were found to be comprised of an inner and outer belt extending up to 25,000 miles above Earth's surface. In 2013, [Daniel] Baker -- who received his doctorate under Van Allen -- led a team that used the twin Van Allen Probes launched by NASA in 2012 to discover a third, transient "storage ring" between the inner and outer Van Allen radiation belts that seems to come and go with the intensity of space weather.-"The latest mystery revolves around an "extremely sharp" boundary at the inner edge of the outer belt at roughly 7,200 miles in altitude that appears to block the ultrafast electrons from breeching the shield and moving deeper towards Earth's atmosphere.-"'It's almost like theses electrons are running into a glass wall in space," said Baker, the study's lead author. "Somewhat like the shields created by force fields on Star Trek that were used to repel alien weapons, we are seeing an invisible shield blocking these electrons. It's an extremely puzzling phenomenon."
Privileged Planet: Magnetic field
by David Turell , Wednesday, April 15, 2015, 18:38 (3298 days ago) @ David Turell
Our magnetic field is a result of our nickel-iron core movements plus its appears lots of uranium. This plus our atmosphere protects us from all the nasty rays that fly around the universe and the Milky Way:-http://www.nature.com/nature/journal/v520/n7547/full/520299a.html?WT.ec_id=NATURE-20150416-Note editors comments and the other link
Privileged Planet: New study
by David Turell , Wednesday, July 22, 2015, 16:36 (3200 days ago) @ David Turell
Why we are different from Venus:-http://wattsupwiththat.com/2015/07/22/why-we-live-on-earth-and-not-venus/-"The research, published this week in Nature Geoscience, suggests that Earth's first crust, which was rich in radioactive heat-producing elements such as uranium and potassium, was torn from the planet and lost to space when asteroids bombarded the planet early in its history. This phenomenon, known as impact erosion, helps explain a landmark discovery made over a decade ago about the Earth's composition.-"Researchers with the University of British Columbia and University of California, Santa Barbara say that the early loss of these two elements ultimately determined the evolution of Earth's plate tectonics, magnetic field and climate.- “'The events that define the early formation and bulk composition of Earth govern, in part, the subsequent tectonic, magnetic and climatic histories of our planet, all of which have to work together to create the Earth in which we live,” said Mark Jellinek, a professor in the Department of Earth, Ocean & Atmospheric Sciences at UBC. “It's these events that potentially differentiate Earth from other planets.”-"On Earth, shifting tectonic plates cause regular overturning of Earth's surface, which steadily cools the underlying mantle, maintains the planet's strong magnetic field and stimulates volcanic activity. Erupting volcanoes release greenhouse gases from deep inside the planet and regular eruptions help to maintain the habitable climate that distinguishes Earth from all other rocky planets.-"Venus is the most similar planet to Earth in terms of size, mass, density, gravity and composition. While Earth has had a stable and habitable climate over geological time, Venus is in a climate catastrophe with a thick carbon dioxide atmosphere and surface temperatures reaching about 470 C. In this study, Jellinek and Matt Jackson, an associate professor at the University of California, explain why the two planets could have evolved so differently.- “'Earth could have easily ended up like present day Venus,” said Jellinek. “A key difference that can tip the balance, however, may be differing extents of impact erosion.'”
Privileged Planet: comparing solar systems
by David Turell , Tuesday, February 02, 2016, 05:40 (3006 days ago) @ David Turell
Only six percent of ones seen are like ours and have gas giants like Jupiter:-http://www.forbes.com/sites/brucedorminey/2016/01/31/solar-systems-like-ours-remain-scarce/#73d456b01d58-" Solar systems like ours, in which Jupiter-like planets orbit their parent stars at Jupiter-like distances, remain scarce in the local stellar neighborhood, says an Australian-led team of astronomers.-***-"They confirms that 17 years of data taken with the 3.9-meter Anglo-Australian Telescope in Australia, indicates that only some 6.2 percent of 202 nearby solar type harbor Jupiter analogs. That is, gas giant planets that would circle their stars on Jupiter-like orbits of 3 to 5 astronomical units (AU), or Earth-Sun distances. Our own Jupiter lies at 5.2 AU, which means it orbits our Sun roughly once every 12 years.-"As Robert Wittenmyer, an astronomer at the University of New South Wales in Sydney and the paper's lead author told me, NASA 's Kepler space telescope has shown us that small planets appear to be ubiquitous. But he says very few observers are looking at what he terms the other half of the question, the long-period gas giants.-***-"The findings are important because conventional theories of planet formation have usually dictated that gas giants like Jupiter parked in a stable, rather distant, orbit from its parent star were thought to be key to the onset of life on closer-in Earth-like planets.-***-"As Wittenmyer notes their latest results confirm earlier data from 2010 that statistically few systems harbor true Jupiter analogs.-“'This tells us that the architecture of our solar system, with nearly-circular outer gas giants and room for inner terrestrial planets, is relatively uncommon?? ,” said Wittenmyer.-"Even so, Jupiter's presence can be a double-edged sword.-"As the paper points out, although Jupiter can act to shield Earth from incoming comets and asteroids, it can also act to “control the flux of small bodies to the inner solar system, acting to perturb” such objects onto Earth-crossing orbits.-“'Jupiter doesn't just eject things from the solar system, taking them off Earth-crossing orbits,” said Horner. “But it also throws things our way that would otherwise have come nowhere near our planet.”-"So, are habitable extrasolar Earths possible without such Jupiters?-“'You could certainly have Earth-sized planets without [gas giants] beyond,” said Horner. “But without a Jupiter-like planet to throw volatile-rich objects toward that planet, it may not be able to get a significant amount of water. Earth without Jupiter might be a very different place with fewer impacts perhaps, but far more arid and inhospitable.'”-Comment: Our Earth is very different and very special, and it looks like our solar system is quite unusual, which fits the pattern that life needs a very special place to develop. The Earth is two-thirds of the way out on the second spiral arm, a quiet place in the Milky Way without too much radiation or explosions.
Privileged Planet: comparing solar systems
DAVID: Only six percent of ones seen are like ours and have gas giants like Jupiter:-http://www.forbes.com/sites/brucedorminey/2016/01/31/solar-systems-like-ours-remain-sca...-QUOTE: "Solar systems like ours, in which Jupiter-like planets orbit their parent stars at Jupiter-like distances, remain scarce in the local stellar neighborhood, says an Australian-led team of astronomers." David's comment: Our Earth is very different and very special, and it looks like our solar system is quite unusual, which fits the pattern that life needs a very special place to develop. The Earth is two-thirds of the way out on the second spiral arm, a quiet place in the Milky Way without too much radiation or explosions. -Definitely different, definitely special. It makes you wonder why in heaven your God had to make all those billions of ordinary, same-old, non-special solar systems that don't seem to do anything for anyone. (Apparently they're all there for our sake, though only he knows why.) Or maybe...maybe...we just got lucky...
Privileged Planet: comparing solar systems
by David Turell , Tuesday, February 02, 2016, 19:24 (3005 days ago) @ dhw
David's comment: Our Earth is very different and very special, and it looks like our solar system is quite unusual, which fits the pattern that life needs a very special place to develop. The Earth is two-thirds of the way out on the second spiral arm, a quiet place in the Milky Way without too much radiation or explosions. > > > dhw: Definitely different, definitely special. It makes you wonder why in heaven your God had to make all those billions of ordinary, same-old, non-special solar systems that don't seem to do anything for anyone. (Apparently they're all there for our sake, though only he knows why.) Or maybe...maybe...we just got lucky...-Like debating the design of the retina as 'unfortunately backwards', we find it is better that way. Perhaps we will discover why the universe is necessarily built like it is. You are a good second guesser.
Privileged Planet: comparing solar systems
David's comment: Our Earth is very different and very special, and it looks like our solar system is quite unusual, which fits the pattern that life needs a very special place to develop. The Earth is two-thirds of the way out on the second spiral arm, a quiet place in the Milky Way without too much radiation or explosions.-dhw: Definitely different, definitely special. It makes you wonder why in heaven your God had to make all those billions of ordinary, same-old, non-special solar systems that don't seem to do anything for anyone. (Apparently they're all there for our sake, though only he knows why.) Or maybe...maybe...we just got lucky...-DAVID: Like debating the design of the retina as 'unfortunately backwards', we find it is better that way. Perhaps we will discover why the universe is necessarily built like it is. You are a good second guesser.-You may as well say perhaps we will discover that God exists. Or perhaps we will discover that life can generate itself. Such “perhapses” are neither rational nor scientific. I am not second-guessing. You begin with the premise that God exists, and therefore there has to be a divine reason for everything you see. I begin with what I see, and look for reasons. The fact that I am extremely short-sighted does not mean that I should stop looking, or that there are divine reasons for me to find!
Privileged Planet: comparing solar systems
by David Turell , Wednesday, February 03, 2016, 15:38 (3004 days ago) @ dhw
> dhw: You may as well say perhaps we will discover that God exists. Or perhaps we will discover that life can generate itself. Such “perhapses” are neither rational nor scientific. I am not second-guessing. You begin with the premise that God exists, and therefore there has to be a divine reason for everything you see. I begin with what I see, and look for reasons. The fact that I am extremely short-sighted does not mean that I should stop looking, or that there are divine reasons for me to find!-Are you forgetting that I began my search by looking at what I see, studying the science behind it and concluded what we see requires a mind to plan it?
Privileged Planet: comparing solar systems
dhw: You may as well say perhaps we will discover that God exists. Or perhaps we will discover that life can generate itself. Such “perhapses” are neither rational nor scientific. I am not second-guessing. You begin with the premise that God exists, and therefore there has to be a divine reason for everything you see. I begin with what I see, and look for reasons. The fact that I am extremely short-sighted does not mean that I should stop looking, or that there are divine reasons for me to find!-DAVID: Are you forgetting that I began my search by looking at what I see, studying the science behind it and concluded what we see requires a mind to plan it? -No, I have not forgotten. But you have ended your search and are now seeking to justify your conclusion even in the face of factors you cannot explain. And you have added to your conclusion (that there is a God) various hypotheses that have nothing to do with your study of science: e.g. your interpretation of your God's purpose (humans), his method (preprogramming or dabbling), the extent of his power (control over billions of solar systems). Of course you have every right to draw a conclusion, as do our atheist friends, but you both have to shut one eye when you “look at what you see”. That is certainly more challenging than shutting both eyes (ugh, who cares?), and it may be more satisfying than looking with both eyes (um...which way?), but I question whether it is more rational and more scientific.
Privileged Planet: comparing solar systems
by David Turell , Thursday, February 04, 2016, 15:52 (3003 days ago) @ dhw
> DAVID: Are you forgetting that I began my search by looking at what I see, studying the science behind it and concluded what we see requires a mind to plan it? > > > dhw: No, I have not forgotten. But you have ended your search and are now seeking to justify your conclusion even in the face of factors you cannot explain. And you have added to your conclusion (that there is a God) various hypotheses that have nothing to do with your study of science: e.g. your interpretation of your God's purpose (humans), his method (preprogramming or dabbling), the extent of his power (control over billions of solar systems).-I have looked at the arrival of humans scientifically. That is why I know it is God's purpose. Time limits to develop and difference in kind. Why I have to know his method of evolutionary development is your demand, not mine. Read the entry from Denton today. And fine-tuning of the universe, per Leslie, is also evidence for God.
Privileged Planet: comparing solar systems
DAVID: Are you forgetting that I began my search by looking at what I see, studying the science behind it and concluded what we see requires a mind to plan it? dhw: No, I have not forgotten. But you have ended your search and are now seeking to justify your conclusion even in the face of factors you cannot explain. And you have added to your conclusion (that there is a God) various hypotheses that have nothing to do with your study of science: e.g. your interpretation of your God's purpose (humans), his method (preprogramming or dabbling), the extent of his power (control over billions of solar systems).-DAVID: I have looked at the arrival of humans scientifically. That is why I know it is God's purpose. Time limits to develop and difference in kind. Why I have to know his method of evolutionary development is your demand, not mine. Read the entry from Denton today. And fine-tuning of the universe, per Leslie, is also evidence for God.-Strange! I have heard that there are some scientists who have looked at the arrival of humans scientifically but have concluded that there is no God and no purpose, and there are others who, like Denton, are undecided. It seems that looking at things scientifically can lead to different conclusions. For the rest, see my reply on the Denton thread.
Privileged Planet: very early Earth
by David Turell , Monday, May 08, 2017, 18:50 (2544 days ago) @ dhw
A study of zircons from 4.4 billion years ago in Australia describers a flat earth, mostly covered with water:
https://www.sciencedaily.com/releases/2017/05/170508112409.htm
"Scientists at The Australian National University (ANU) say the early Earth was likely to be barren, flat and almost entirely under water with a few small islands, following their analysis of tiny mineral grains as old as 4.4 billion years.
"Lead researcher Dr Antony Burnham said the team studied zircon mineral grains that were preserved in sandstone rocks in the Jack Hills of Western Australia and which were the oldest fragments of the Earth ever found.
"The history of the Earth is like a book with its first chapter ripped out with no surviving rocks from the very early period, but we've used these trace elements of zircon to build a profile of the world at that time," said Dr Burnham from the ANU Research School of Earth Sciences.
"'Our research indicates there were no mountains and continental collisions during Earth's first 700 million years or more of existence -- it was a much more quiet and dull place.
"'Our findings also showed that there are strong similarities with zircon from the types of rocks that predominated for the following 1.5 billion years, suggesting that it took the Earth a long time to evolve into the planet that we know today."
"Dr Burnham said the zircon grains that eroded out of the oldest rocks were like skin cells found at a crime scene.
"'We used the granites of southeast Australia to decipher the link between zircon composition and magma type, and built a picture of what those missing rocks were," he said.
"The first known form of life emerged some time later, around 3.8 billion years ago.
Dr Burnham said the zircon formed by melting older igneous rocks rather than sediments.
"'Sediment melting is characteristic of major continental collisions, such as the Himalayas, so it appears that such events did not occur during these early stages of Earth's history," he said.
"Dr Burnham said scientists in the field were able to build on each other's work to gain a better understanding of early Earth."
Comment: In this period before life there is no evidence of plate tectonics forming floating continents to bump into each other and make Earth's crust lump enough to have oceans and continents. Yet life appeared in those oceans about 3.8 billion years ago. How solid was the Earth's crust? If it took 1.5 billion years for Earth's origin to change to plates, this raises the issue of whether volcanic vents were present to help life form, which is one of the popular current theories for life's arrival.
Privileged Planet: very early Earth
by David Turell , Thursday, March 29, 2018, 18:07 (2219 days ago) @ David Turell
New study says it had lots of water very early:
https://www.newscientist.com/article/2165141-earth-had-water-even-before-the-collision-...
"Earth may have had water for far longer than we thought. The planet may have had lakes and oceans even before the giant impact that created the moon, and it could have survived that colossal collision.
"Previously it was thought that most, or even all, of Earth’s ocean water was carried to the planet on comets and asteroids after the moon was formed. But Richard Greenwood at the Open University in Milton Keynes and his colleagues found that it might have already been here.
"Greenwood and his colleagues compared the oxygen composition of moon rocks brought back to Earth by Apollo astronauts with that of volcanic rocks from the ocean floor.
"The presence of liquid water alters the amounts of different oxygen isotopes in the rock. So, if most of the water on Earth had arrived after the giant impact, the rocks should have distinctly different oxygen compositions. The moon rocks should show little sign of being altered by water.
"But Greenwood and his team detected only a small difference between the lunar and terrestrial rocks.
"This suggests that liquid water must have existed on Earth before its moon-forming collision with a body the size of Mars, which is thought to have occurred about 100 million years after the solar system formed. The researchers found that most of the water we have now may have already been here, and then between 5 and 30 per cent of it was brought later by asteroids and comets.
"Other work has shown that many distant worlds in other star systems underwent similar collisions early in their evolution, events which we thought meant they could not have liquid water unless it was delivered later on.
"The fact that liquid water can survive catastrophic impacts by planet-sized bodies means it should be abundant on worlds in other star systems, Greenwood says. Life as we know it requires water, so this could make those exoplanets more hospitable."
Comment: Our planet is obviously built to support life. Since life appeared here at least 3.8 billion years ago water had to be here in large amounts. More evidence of God's planning for life to appear.
Privileged Planet: we have useful phosphorus
by David Turell , Friday, April 06, 2018, 14:56 (2211 days ago) @ David Turell
Our form of life requires abundant phosphorus. We have it but there is not much in he rest of the universe:
http://www.techtimes.com/articles/224437/20180405/substantial-lack-of-phosphorus-in-the...
"Phosphorus is the 11th most common element on Earth, and it is fundamental to all living things. Phosphorus is one of only six chemical elements on our planet that organisms depend on.
"[Phosphorus] helps form the backbone of the long chains of nucleotides that create RNA and DNA; it is part of the phospholipids in cell membranes; and is a building block of the coenzyme used as an energy carrier in cells, adenosine triphosphate (ATP)," NASA said.
"Astronomers have been hunting for phosphorus in the universe because of the role it plays in life on Earth. If the element is lacking in other parts of the cosmos, it could be difficult for alien life to exist.
"A new study presented at the European Week of Astronomy and Space Science meeting now suggests that life as we know it is more unusual than previously thought because the universe substantially lacks phosphorus.
"Study researcher Jane Greaves, from the University of Cardiff, and colleagues, found that the reason our planet got enough of the element is because it is close enough to a supernova.
"Phosphorus is formed in supernovae when massive stars explode at the end of their lives, but the researchers found that the typical supernova may not provide the right conditions to forge the element. Earth just happened to be in close proximity to the right kind of supernova, making it unusually lucky.
"The researchers made their conclusion based on observations of two supernova remnants, the Crab Nebula and Cassiopeia A (Cas A). The found that Cas A appears to have more phosphorus than Crab Nebula. The researchers theorize that the latter had more reactions that made phosphorus because it was denser or more massive.
"The findings hint that material blown out into space may dramatically vary in composition. The researchers said that some of the phosphorus-bearing minerals such as those in meteorites that came to Earth may have been reactive enough to contribute to the making of proto-biomolecules.
"If phosphorus comes from supernova and travels across space in meteoritic rock, the researchers wondered if young planets near the wrong kind of supernova may find themselves lacking in reactive phosphorus.
"'In that case, life might really struggle to get started out of phosphorus-poor chemistry, on another world otherwise similar to our own," Greaves said."
Comment: Are we just a lucky planet or were our special characteristics planned? We are living here because the Earth is so special.
Privileged Planet: p;ate tectonics and 'snowball Earth'
by David Turell , Tuesday, May 08, 2018, 01:08 (2180 days ago) @ David Turell
About 700-800 million years ago the Earth was a snowball of ice and snow all over. The start of plate tectonics might have caused it by creating volcanism and blotting out the sun with the eruptions:
https://www.sciencedaily.com/releases/2018/05/180507153141.htm
"Plate tectonics is a theory formulated in the late 1960s that states the Earth's crust and upper mantle -- a layer called the lithosphere -- is broken into moving pieces, or plates. These plates move very slowly -- about as fast as your fingernails and hair grow -- causing earthquakes, mountain ranges and volcanoes.
"Earth is the only body in our solar system known to currently have plate tectonics, where the lithosphere is fragmented like puzzle pieces that move independently," said Dr. Robert Stern, professor of geosciences in UT Dallas' School of Natural Sciences and Mathematics, and co-author of the study, along with Dr. Nathaniel Miller, a research scientist in UT Austin'
"'It is much more common for planets to have an outer solid shell that is not fragmented, which is known as 'single lid tectonics'," Stern said.
"Geoscientists disagree about when the Earth changed from single lid to plate tectonics, with the plate fragmenting from one plate to two plates and so on to the present global system of seven major and many smaller plates. But Stern highlights geological and theoretical evidence that plate tectonics began between 800 million and 600 million years ago, and has published several articles arguing for this timing.
***
"'We went through the literature and examined all the mechanisms that have been put forward for Snowball Earth," Stern said. "The start of plate tectonics could be responsible for each of these explanations."
"The onset of plate tectonics should have disturbed the oceans and the atmosphere by redistributing continents, increasing explosive arc volcanism and stimulating mantle plumes, Stern said.
"'The fact that strong climate and oceanographic effects are observed in the Neoproterozoic time is a powerful supporting argument that this is indeed the time of the transition from single lid to plate tectonics," Stern said. "It's an argument that, to our knowledge, hasn't yet been considered."
Comment: This special planet has a moving crust. None of our neighbors have it. It is a requirement for life. Further note how tough life it. It survived the freeze.
Privileged Planet: when land masses appeared
by David Turell , Friday, May 25, 2018, 21:12 (2162 days ago) @ David Turell
Dated from shale samples all over the Earth. 2.4 billion years ago:
https://www.sciencedaily.com/releases/2018/05/180523133221.htm
"Chemical signatures in shale, the Earth's most common sedimentary rock, point to a rapid rise of land above the ocean 2.4 billion years ago that possibly triggered dramatic changes in climate and life.
"In a study published in the May 24 issue of the journal Nature, researchers report that shale sampled from around the world contains archival quality evidence of almost imperceptible traces of rainwater that caused weathering of land from as old as 3.5 billion years ago.
***
'Based on his own previous modeling and other studies, Bindeman said, total landmass on the planet 2.4 billion years ago may have reached about two-thirds of what is observed today. However, the emergence of the new land happened abruptly, in parallel with large-scale changes in mantle dynamics.
"Isotopic changes recorded in the shale samples at that time also coincides with the hypothesized timing of land collisions that formed Earth's first supercontinent, Kenorland, and high-mountain ranges and plateaus.
"Crust needs to be thick to stick out of water," Bindeman said. "The thickness depends on its amount and also on thermal regulation and the viscosity of the mantle. When the Earth was hot and the mantle was soft, large, tall mountains could not be supported. Our data indicate that this changed exponentially 2.4 billion years ago. The cooler mantle was able to support large swaths of land above sea level."
"Temperatures on the surface when the new land emerged from the sea would have likely been hotter than today by several tens of degrees, he said.
***
"At 2.4 billion years ago, Bindeman said, the newly emerged land began to consume carbon dioxide from the atmosphere amid chemical weathering.
"The timing also coincides with the transition from the Archean Eon, when simple prokaryotic life forms, archaea and bacteria, thrived in water, to the Proterozoic Eon, when eukaryotes, such as algae, plants and fungi, emerged.
"In this study, we looked at how weathering proceeded over 3.5 billion years," Bindeman said.
"'Land rising from water changes the albedo of the planet. Initially, Earth would have been dark blue with some white clouds when viewed from space. Early continents added to reflection. Today we have dark continents because of lots of vegetation."
"Exposure of the new land to weathering, he said, may have set off a sink of greenhouse gases such carbon dioxide, disrupting the radiative balance of the Earth that generated a series of glacial episodes between 2.4 billion and 2.2 billion years ago. That, he said, may have spawned the Great Oxygenation Event in which atmospheric changes brought significant amounts of free oxygen into the air. Rocks were oxidized and became red. Archean rocks are gray.
***
"'What we speculate is that once large continents emerged, light would be reflected back into space and initiate runaway glaciation," Bindeman said. "Earth would have seen its first snowfall."
"Shales are formed by the weathering of crust.
"They tell you a lot about the exposure to air and light and precipitation," Bindeman said.
"'The process of forming shale captures organic products and eventually helps to generate oil. Shales provide us with a continuous record of weathering.'"
Comment: The Earth is different because of its floating crust and split into various plates which bump into each other and cause elevations by subduction.
Privileged Planet: when land masses appeared
QUOTES: 'Based on his own previous modeling and other studies, Bindeman said, total landmass on the planet 2.4 billion years ago may have reached about two-thirds of what is observed today. However, the emergence of the new land happened abruptly, in parallel with large-scale changes in mantle dynamics.
"At 2.4 billion years ago, Bindeman said, the newly emerged land began to consume carbon dioxide from the atmosphere amid chemical weathering.
"The timing also coincides with the transition from the Archean Eon, when simple prokaryotic life forms, archaea and bacteria, thrived in water, to the Proterozoic Eon, when eukaryotes, such as algae, plants and fungi, emerged.
"Exposure of the new land to weathering, he said, may have set off a sink of greenhouse gases such carbon dioxide, disrupting the radiative balance of the Earth that generated a series of glacial episodes between 2.4 billion and 2.2 billion years ago. That, he said, may have spawned the Great Oxygenation Event in which atmospheric changes brought significant amounts of free oxygen into the air.
I’ve cherry-picked these quotes, as I’m interested in the suddenness of environmental change coinciding with the emergence of new life forms. It seems to me that this offers a vital clue as to how evolution has progressed: once the mechanism for life, reproduction and change was in place (we needn’t concern ourselves here with the origin of the mechanism), organisms would have responded to those changes in one of three ways: extinction, adaptation, innovation. This could have taken place on a local as well as a global level.
Privileged Planet: when land masses appeared
by David Turell , Saturday, May 26, 2018, 15:08 (2161 days ago) @ dhw
QUOTES: 'Based on his own previous modeling and other studies, Bindeman said, total landmass on the planet 2.4 billion years ago may have reached about two-thirds of what is observed today. However, the emergence of the new land happened abruptly, in parallel with large-scale changes in mantle dynamics.
"At 2.4 billion years ago, Bindeman said, the newly emerged land began to consume carbon dioxide from the atmosphere amid chemical weathering.
"The timing also coincides with the transition from the Archean Eon, when simple prokaryotic life forms, archaea and bacteria, thrived in water, to the Proterozoic Eon, when eukaryotes, such as algae, plants and fungi, emerged.
"Exposure of the new land to weathering, he said, may have set off a sink of greenhouse gases such carbon dioxide, disrupting the radiative balance of the Earth that generated a series of glacial episodes between 2.4 billion and 2.2 billion years ago. That, he said, may have spawned the Great Oxygenation Event in which atmospheric changes brought significant amounts of free oxygen into the air.
dhw: I’ve cherry-picked these quotes, as I’m interested in the suddenness of environmental change coinciding with the emergence of new life forms. It seems to me that this offers a vital clue as to how evolution has progressed: once the mechanism for life, reproduction and change was in place (we needn’t concern ourselves here with the origin of the mechanism), organisms would have responded to those changes in one of three ways: extinction, adaptation, innovation. This could have taken place on a local as well as a global level.
It took a while for land organisms to appear. Fossils we find on land now were originally under water.
Privileged Planet: where nitrogen is stored
by David Turell , Tuesday, May 29, 2018, 20:53 (2158 days ago) @ David Turell
It is hidden in rocks, a site not recognized before. Basic amino acids have carbon, oxygen, hydrogen, nitrogen, often sulfur, as basic parts of the molecule:
https://www.scientificamerican.com/article/mystery-of-earths-missing-nitrogen-solved/?u...
"Experts used to think nearly all nitrogen in soil came directly from the atmosphere, sequestered by microbes or dissolved in rain. But it turns out scientists have been overlooking another major source of this element, which is crucial to plant growth: up to a quarter of the nitrogen in soil and plants seeps out of bedrock,
***
"Beginning in the 1970s, a few studies showed that several types of sedimentary rock contain nitrogen from long-dead plants, algae and animals deposited on the ancient seafloor. A handful of papers suggested the element might leach into soil in certain places. But scientists did not follow up on these findings, and the amount of nitrogen released as rocks weather was thought to be insignificant.
***
" In their new study, Houlton and his colleagues used California as a model geologic system because the state contains most of the planet’s rock types. They measured nitrogen levels in nearly 1,000 Californian samples and in others from around the globe. They then developed a computer model to calculate how quickly the earth’s rocks break down and release nitrogen into the soil.
"Nitrogen liberated by weathering processes eventually makes its way to the ocean, where it is deposited in rocks as they form on the seafloor. Tectonic plate movement lifts up the rocks; they degrade and release their nitrogen, which gets absorbed by plants and animals and trapped in rocks again—perpetuating the cycle. Weathering can involve both physical breakdown—which is accelerated when rocks are thrust upward and exposed to the elements as mountain ranges—and chemical dissolution, such as when acidic rainwater reacts with compounds in rocks."
Comment: Another way the Earth is designed to produce protein-based life. Looking at this in the reverse, can life appear if a planet isn't set up like the Earth?
Privileged Planet: how the magnetic field protects us
by David Turell , Thursday, May 31, 2018, 22:55 (2156 days ago) @ David Turell
It is by heating up electrons as we orbit in to the solar wind:
https://phys.org/news/2018-05-earth-solar-gentle-breeze.html
"As Earth orbits the sun at supersonic speed, it cuts a path through the solar wind. This fast stream of charged particles, or plasma, launched from the sun's outer layers would bombard Earth's atmosphere if not for the protection of Earth's magnetic field.
"Just as a motorboat creates a bow-shaped wave ahead of itself as the hull pushes through the water, Earth creates a similar effect—called a bow shock—as it pushes through the solar wind. Scientists have sought to explain how Earth's magnetic field can shove aside the powerful solar wind without unleashing calamity. They have known part of the answer for a long time: the bow shock converts energy from the solar wind to heat stored in electrons and ions. But now, researchers have important new clues about how this process occurs.
"A University of Maryland-led study describes the first observations of the process of electron heating in Earth's bow shock. The researchers found that when the electrons in the solar wind encounter the bow shock, they momentarily accelerate to such a high speed that the electron stream becomes unstable and breaks down. This breakdown process robs the electrons of their high speed and converts the energy to heat.
"The results add an important new dimension to scientists' understanding of Earth's magnetic field and its ability to protect the planet from harmful particles and radiation.
***
"'If you were to stand on a mountaintop, you might get knocked over by a fast wind," explained Li-Jen Chen, lead author of the study and an associate research scientist in the UMD Department of Astronomy. "Fortunately, as the solar wind crashes into Earth's magnetic field, the bow shock protects us by slowing down this wind and changing it to a nice, warm breeze. We now have a better idea how this happens."
***
"Seizing on this advantage, the researchers observed the solar wind's electron stream before, during and after meeting with the bow shock. The electron stream accelerated by the shock only took 90 milliseconds to destabilize and fully break down.
"'The study of electron heating is important not just for understanding how the bow shock protects Earth, but potentially for satellites, space travel and maybe exploring other planets in the future," Chen said.
"By giving the first clear picture of what electrons at the bow shock are doing, Chen and her collaborators hope to encourage other scientists to perform computer simulations, further space observations and laboratory experiments on electron heating. Chen also looks forward to delving further into the mechanisms by which the bow shock accelerates the electron stream."
Comment: We continue to find reasons why he Earth is perfectly designed for life.
Privileged Planet: plate tectonics explained
by David Turell , Friday, June 08, 2018, 20:05 (2148 days ago) @ David Turell
A very long thorough article on how important it is to start and maintain life:
https://www.quantamagazine.org/plate-tectonics-may-be-essential-for-life-20180607/
"But there’s more to plate tectonics than earthquakes and eruptions. A wave of new research is increasingly hinting that Earth’s external motions may be vital to its other defining feature: life. That Earth has a moving, morphing outer crust may be the main reason why Earth is so vibrant, and why no other planet can match its abundance.
“'Understanding plate tectonics is a major key to understanding our own planet and its habitability. How do you make a habitable planet, and then sustain life on it for billions of years?” said Katharine Huntington, a geologist at the University of Washington. “Plate tectonics is what modulates our atmosphere at the longest timescales. You need that to be able to keep water here, to keep it warm, to keep life chugging along.”
"In the past few years, geologists and astrobiologists have increasingly tied plate tectonics to everything else that makes Earth unique. They have shown that Earth’s atmosphere owes its longevity, its components, and its incredibly stable Goldilocks-like temperature — not too hot, but not too cold — to the recycling of its crust. Earth’s oceans might not exist if water were not periodically subsumed by the planet’s mantle and then released. Without plate tectonics driving the creation of coastlines and the motion of the tides, the oceans might be barren, with life-giving nutrients relegated forever to the stygian depths. If plate tectonics did not force slabs of rock to dive underneath one another and back into the Earth, a process called subduction, then the seafloor would be entirely frigid and devoid of interesting chemistry, meaning life might never have taken hold in the first place. Some researchers even believe that without the movement of continents, life might not have evolved into complex forms.
***
"In December 2015, researchers in Australia published a study of roughly 300 drill cores from seafloor sites around the globe, some containing samples that were 700 million years old. They measured phosphorus as well as trace elements like copper, zinc, selenium and cobalt — nutrients that are essential for all life. When these nutrients are abundant in the oceans, they can spark rapid plankton growth. The researchers, led by Ross Large of the University of Tasmania, showed that these elements increased in concentration by an order of magnitude around 560 to 550 million years ago.
Large and his team argue that plate tectonics drove this process. Mountains form when continental plates collide and shove rock skyward, where it can more readily be battered by rain. Weathering then slowly leaches nutrients from the mountains into the oceans.
***
"Tectonic activity also plays an essential role in maintaining the long-term stability of Earth’s thermostat. Consider the case of carbon dioxide. A planet with too much carbon dioxide could end up like Venus, a planetary blast furnace. Plate activity on Earth has helped to regulate the level of carbon dioxide over the eons.
***
"According to research published in 2016, plate tectonics then initiated a two-step process that led to higher oxygen levels. In the first step, subduction causes the Earth’s mantle to change and produce two types of crust — oceanic and continental. The continental version has fewer iron-rich rocks and more quartz-rich rocks that don’t pull oxygen out of the atmosphere.
"Then over the next billion years — from 2.5 billion years ago to 1.5 billion years ago — rocks weathered down and pumped carbon dioxide into the air and oceans. The extra carbon dioxide would have aided algae, which then could make even more oxygen — enough to eventually spark the Cambrian explosion.
***
"According to these theories, plate tectonics may have started and stopped several times before picking up momentum about 3 billion years ago. “If you had to press everyone’s buttons and make them take a number, there’s a running ballpark in the community that around 3 billion years ago, plate tectonics started emerging,” O’Neill said.
"Yet it’s hard to know for sure because the evidence is so fragmentary.
***
"O’Neill has come to think of plate tectonics as a middle-age phase for rocky planets. As a planet ages, it may evolve from a hot, stagnant world to a warm, tectonically active one, and finally to a cold, stagnant one again in its later years. We know planets can grow quiet as they cool down; many geologists think this is what happened to Mars, which cooled off faster than Earth because it is so much smaller."
Comment: Huge article worth reading all. Earth looks especially designed for life.
Privileged Planet: plate tectonics explained
DAVID: A very long thorough article on how important it is to start and maintain life:
https://www.quantamagazine.org/plate-tectonics-may-be-essential-for-life-20180607/
QUOTE: "But there’s more to plate tectonics than earthquakes and eruptions. A wave of new research is increasingly hinting that Earth’s external motions may be vital to its other defining feature: life. That Earth has a moving, morphing outer crust may be the main reason why Earth is so vibrant, and why no other planet can match its abundance.
“'Understanding plate tectonics is a major key to understanding our own planet and its habitability. How do you make a habitable planet, and then sustain life on it for billions of years?” said Katharine Huntington, a geologist at the University of Washington. “Plate tectonics is what modulates our atmosphere at the longest timescales. You need that to be able to keep water here, to keep it warm, to keep life chugging along.”
DAVID’s comment: Huge article worth reading all. Earth looks especially designed for life.
Once again, I can only thank you for this very illuminating article and for editing it to manageable proportions.
Privileged Planet: our tilt helps life
by David Turell , Thursday, June 21, 2018, 14:50 (2135 days ago) @ dhw
We are tilted 23.5 degrees from upright. it makes seasons and makes life here much easier to survive:
https://www.nytimes.com/2018/06/20/science/summer-solstice-2018-meaning-sunset.html?emc...
"The solstice occurs because Earth does not spin upright but leans 23.5 degrees on a tilted axis. Such a slouch, or obliquity, has long caused astronomers to wonder whether Earth’s tilt — which you could argue is in a sweet spot between more extreme obliquities — helped create the conditions necessary for life.
***
"If the planet had no slouch, it wouldn’t have seasons. The hemispheres would never dip toward or away from their star. Instead, the poles (which always point toward the frigid depths of space) would be so cold that carbon dioxide would be pulled from the sky, an effect, Dr. Heller argues, that would cause the planet to lose its precious greenhouse gas so that liquid water could never form.
***
"David Ferreira, an oceanographer at the University of Reading in England, invoked a similar argument. In 2014, he and his colleagues found that even an Earth 2.0 with a slouch as low as Uranus’s could potentially support life — so long as the planet had a global ocean.
An ocean will absorb heat during summer, then when winter arrives it will release that heat, allowing the planet to stay relatively temperate.
“'It’s a bit like when you put a stone in the fire and it gets really hot,” Dr. Ferreira says.
“'If you take that stone out of the fire, it’s going to release that heat slowly.” That allows the water world to experience balmy springlike temperatures year-round.
***
"Take Earth as an example. Although our planet’s obliquity is relatively constant, it does change by a mere few degrees. Such slight variations have sent vast sheets of glaciers from the poles to the tropics and entombed Earth within a frozen skin of solid ice. Luckily, Earth has managed to escape these so-called snowball states. But scientists are not sure whether the same will be true for planets like Mars with larger variations in their tilts.
"In 2018, a team of astronomers argued that wild variations could push a planet toward an inescapable snowball state, even if it resided within a star’s habitable zone — that goldilocks band where liquid water can typically exist.
"As such, a stable tilt just might be a necessary ingredient for life. It’s an interesting finding given that the Earth’s tilt never changes drastically thanks to the Moon. And yet astronomers don’t know how common such moons are within the galaxy, said John Armstrong, an astronomer at Weber State University in Utah. If they turn out to be uncommon across the galaxy, it could mean that such stability — and therefore life — is hard to come by.
***
“'This planet is really on the verge of destruction all the time,” he said. Although Earth is considered stable, it has still suffered global glaciations and meteorite impacts — and yet life has survived. That could mean that life is hardier than you might expect. But it could also mean that further variations would push it over the edge."
Comment: More evidence that the Earth might be specifically designed so life could start.
Privileged Planet: our tilt helps life
by David Turell , Tuesday, July 03, 2018, 18:29 (2123 days ago) @ David Turell
An article on exoplanets explains how our tilt is maintained:
https://www.sciencedaily.com/releases/2018/06/180628151708.htm
"How important is axial tilt for climate? Large variability in axial tilt could be a key reason why Mars transformed from a watery landscape billions of years ago to today's barren desert.
"'Mars is in the habitable zone in our solar system, but its axial tilt has been very unstable -- varying from zero to 60 degrees," said Georgia Tech Assistant Professor Gongjie Li, who led the study together with graduate student Yutong Shan from the Harvard-Smithsonian Center for Astrophysics. "That instability probably contributed to the decay of the Martian atmosphere and the evaporation of surface water."
"As a comparison, Earth's axial tilt oscillates more mildly -- between 22.1 and 24.5 degrees, going from one extreme to the other every 10,000 or so years.
"The orientation angle of a planet's orbit around its host star can be made to oscillate by gravitational interaction with other planets in the same system. If the orbit were to oscillate at the same speed as the precession of the planet's spin axis (akin to the circular motion exhibited by the rotation axis of a top or gyroscope), the spin axis would also wobble back and forth, sometimes dramatically.
"Mars and Earth interact strongly with each other, as well as with Mercury and Venus. As a result, by themselves, their spin axes would precess with the same rate as the orbital oscillation, which may cause large variations in their axial tilt. Fortunately, the moon keeps Earth's variations in check. The moon increases our planet's spin axis precession rate and makes it differ from the orbital oscillation rate. Mars, on the other hand, doesn't have a large enough satellite to stabilize its axial tilt."
Comment: Earth is carefully controlled to allow life. I would strongly suggest designed for life.
Privileged Planet: clouds an interlocked system
by David Turell , Thursday, August 16, 2018, 14:35 (2079 days ago) @ David Turell
On Earth it seems everything and every system are interlocked:
https://cosmosmagazine.com/biology/a-plankton-virus-affects-cloud-formation
"A species of marine phytoplankton that explodes after contracting a virus may play a role in regulating Earth’s climate, a new study finds.
"Emiliania huxleyi is a type of single-celled plant-like organism called a coccolithophore that occurs ubiquitously in the world’s oceans. Under the right conditions, it multiplies rapidly to form giant aggregations, known as blooms, up to several thousand square kilometres in size.
"When these blooms are infected by a virus called, imaginatively enough, the E. huxleyi virus (EhV), the coccolithophores burst. Their calcium carbonate exoskeletons, or coccoliths, are then scattered into the water column.
"Pushed to the surface by bubbles, the exoskeleton fragments are aerosolised, or turned into airborne particles. Research published in the journal iScience by researchers at the Weizmann Institute of Science and Hebrew University of Jerusalem, in Israel, finds that in this state they may help promote cloud formation and potentially alter atmospheric processes.
"The findings reinforce the idea that everything is linked in the Earth system, explains co-author Ilan Koren.
“'Our experiments suggest that ocean ecology can strongly affect fluxes of biological particles to the atmosphere,” he says. “This study shows the huge potential of such links to be important.”
"Marine aerosols are a key component of the planet’s climate system. However, previous studies have disagreed over the degree to which aerosol formation is influenced by localised marine microbial activity. Even less certain is how the interactions between microbial communities — plankton and viruses, for instance — affect the physical and chemical properties of the aerosols that are formed.
***
"The coccoliths’ size and shape help explain why they are so readily airborne. Their large, plate-like structures means that they settle out of the atmosphere at a rate that the authors note, “is about 25 times slower compared with sea salt particles with the same dimension”.
"By staying suspended for longer, the coccoliths increase the window of opportunity for chemical reactions within the atmosphere.
"Moreover, coccoliths surpassed sea salt in terms of their contribution to volume and surface area in the aerosol. Although salt is the dominant inorganic component of marine aerosols, “coccoliths may be as important”, the researchers estimate, when it comes to atmospheric processes that rely on aerosol surface area.
"The study is the first to show that large-scale atmospheric change may be attributable to feedbacks between microscopic organisms during bloom conditions."
Comment: One can certainly make the case that our planet is especially designed with all the interlocking systems that have been demonstrated.
Privileged Planet: life transformed the Earth
by David Turell , Wednesday, October 31, 2018, 18:25 (2003 days ago) @ David Turell
The presence of life has transformed the Earth from a rocky planet into a vibrant living globe through the work of microbes:
https://us-mg205.mail.yahoo.com/neo/launch?.partner=sbc&.rand=a2ucpnsujh5ul#mail
“'Rocks are not nouns, but verbs,” Marcia Bjornerud writes in her superb new geology book “Timefulness.” The ground beneath our feet, the mountains looming overhead, are not static objects, but visible evidence of the processes that shape our planet. The whole story of Earth, from its accretion out of a swirling dust cloud around the sun, through epochs of asteroid bombardments and volcanic explosions and heat and ice and heat again, is inscribed in the layers of rock that have been accumulating like the pages of an unfinished manuscript for 4.6 billion years.
"Against these impassive witnesses to history, life can seem puny and unimportant. The entire human species has existed for less than 1 percent of the age of the Rocky Mountains. Compared with the billion-year-old marble that makes up the Washington Monument, the whole fraught history of the United States has been little more than a blink of an eye.
" Bjornerud writes, life has altered the course of this planet’s history. The invention of photosynthesis by ancient microorganisms completely transformed the planet’s atmosphere from a methane and carbon dioxide rich haze reminiscent of the exhaust from an SUV, into the oxygen-rich air we now know and love. The colonization of land by plants 400 million years ago slowed the pace at which wind and weather wear down mountains and wash bits of rock into the sea. This shift in global erosion rates transformed the way rivers work, creating waterways that carve deep channels through the Earth that exist today. Though only a dozen minerals existed among the ingredients that formed the solar system 4.6 billion years ago, Earth now boasts more than 4,000 mineral species — almost half of which are the result of biology’s interactions with rocks.
"I find these facts poetic and deeply comforting. Tiny, tenacious microbes, working in concert over a billion years, made our planet a more livable place (for oxygen breathing organisms, anyway). A single stubborn pine clinging to some rocky mountainside helps slow its erosion and shape the course of a mighty river.
"Life is not just a product of Earth — Earth is a product of us. As astronomers gaze into the galaxy and beyond, no matter how many small, terrestrial planets orbiting yellow dwarf stars they might find, none of them will be truly Earthlike because none will have had this place’s particular history of being inhabited.
" I find these facts poetic and deeply comforting. Tiny, tenacious microbes, working in concert over a billion years, made our planet a more livable place (for oxygen breathing organisms, anyway). A single stubborn pine clinging to some rocky mountainside helps slow its erosion and shape the course of a mighty river.
"Life is not just a product of Earth — Earth is a product of us. As astronomers gaze into the galaxy and beyond, no matter how many small, terrestrial planets orbiting yellow dwarf stars they might find, none of them will be truly Earthlike because none will have had this place’s particular history of being inhabited."
Comment: Doesn't require a comment. Once life began the transformation is obvious.
Privileged Planet: life transformed the Earth
by Balance_Maintained , U.S.A., Friday, November 02, 2018, 15:24 (2001 days ago) @ David Turell
This whole argument supports my hypothesis for the purpose of early organismal forms in the 'grand design'.
--
What is the purpose of living? How about, 'to reduce needless suffering. It seems to me to be a worthy purpose.
Privileged Planet: life transformed the Earth
by David Turell , Friday, November 02, 2018, 19:37 (2001 days ago) @ Balance_Maintained
Tony: This whole argument supports my hypothesis for the purpose of early organismal forms in the 'grand design'.
Obviously.
Privileged Planet: why does Earth have so much water?
by David Turell , Monday, November 05, 2018, 20:00 (1998 days ago) @ David Turell
Water is vital for life to exist and we have lots of water. The issue is not settled as to how it happened here , but this research indicates most of it appeared early in Earth formation, before the impact that theoretically created the moon, and theoretically from ice containing meteorites and asteroids impacting the early Earth body:
https://www.geologypage.com/2018/04/water-appeared-while-earth-was-still-growing.html
"Up until about ten years ago, scientists thought they had a pretty good picture of how the moon and Earth came to co-exist. Then more precise measurements blew it all wide open, and scientists are still struggling to reconcile them.
"As part of that effort, a team including UChicago cosmochemist Nicolas Dauphas performed the largest study to date of oxygen isotopes in lunar rocks, and found a small but measurable difference in the makeup of the moon and Earth.
"Published March 28 in Science Advances, the research proposes that Earth acquired the majority of its water during the main stage of its growth — which counters a popular theory.
"The most widely accepted theory of the origin of the Moon speculates that a giant object smashed into the proto-Earth at just enough velocity that part of both bodies broke off and formed the moon. The Earth has a little of the moon and the moon has more of the Earth, but they’d be mostly different objects. Early measurements — many taken by the late UChicago geochemist Robert Clayton — did not have sufficient precision to tell the Moon and Earth apart.
"But in the last decade, Dauphas said, it became clear this picture wasn’t quite right. Elements can come in different forms, called isotopes, and these give scientists clues to the rock’s origin. As ways to measure isotopes improved, scientists discovered striking similarities between the moon and the Earth. Referred to as the “lunar isotopic crisis,” this was a problem for the main theory of lunar formation, because it’s highly unlikely the isotopes would be exactly the same for two random objects in the solar system.
***
"Seeking to clarify the issue, the researchers measured the oxygen isotopes of both lunar and terrestrial rocks with extremely high precision. They found a very small, but detectable difference between the isotopes between the two bodies.
***
"Their model suggests that only 5 percent to 30 percent of all the water on Earth would have arrived on meteorites after the great impact."
Comment: Here is a segment of discussion from the original article:
http://oro.open.ac.uk/54309/1/Greenwood%20et%20al%202018.full.pdf
"A late veneer explanation for the 3 to 4 ppm D17O Earth-Moon
difference implies that a large fraction of Earth’s water was delivered
earlier than the giant impact event. Terrestrial hydration would have
been synchronous with the main phase of Earth’s accretion and not
the result of a late-stage delivery of water from the outer solar system
(36). Fortuitously for the evolution of life on our planet, despite the
high energy of the Moon-forming event, Earth retained enough of its
primordial water to remain a habitable environment. These findings
are consistent with modeling studies, which indicate that Earth would
have had an ocean before the era of giant impacts and that this ocean
was retained despite the high energy of this terminal accretion phase."
What this implies to me is a special handling of the Earth to create the enormous volumes of water we have in our oceans and the large subterranean deposits (ocean-sized) recently discovered all of which are vital to the support of life. It is known frozen water is present all over the universe, and some how lots of it is concentrated here in this privileged planet.
Privileged Planet: we have a safe sun
by David Turell , Tuesday, November 06, 2018, 00:04 (1998 days ago) @ David Turell
The rays it supplies are in the right range for us to use:
https://stream.org/nasas-parker-probe-kisses-the-sun-and-rightly-so/
"We should feel very lucky. The sun is a giant fusion bomb, converting hydrogen to helium in an ongoing chain reaction in its dense, ultra-hot core. But fortunately for us, the electromagnetic radiation emitted by this runaway fusion bomb (and that of most other stars) is almost entirely light and heat (or infrared). These have precisely the characteristics needed for advanced life to thrive on the Earth’s surface.
"The crucial visual band, which has the right energy levels for photochemistry, occupies only a tiny part of the electromagnetic (EM) spectrum. To grasp just how small, picture just a few playing cards in a stack stretching from here to beyond the Andromeda galaxy. Andromeda is more than 2.5 million light years away. This playing card illustration, then, represents a fraction so small as to be beyond ordinary human comprehension.
"And here is the key point: It’s thanks only to the fine tuning of the laws and constants of nature that we live in a universe awash in radiation from this tiny swath of the EM spectrum — the life-permitting swath.
Sunlight is also just right for the high-acuity vision we enjoy, thanks to another set of extraordinary coincidences in the characteristics of visual light. And it goes beyond vision. Sunlight is just right in a host of ways for beings of our size and upright android design — for beings who possess the gift of sight, breathe oxygen, and inhabit the terrestrial surface of a planet like the Earth.
***
"As I note there, building on a series of related books, the fine-tuning of sunlight for advanced creatures like ourselves is just one instance of fine-tuning among a growing list in the natural sciences.
"No matter how unfashionable the notion may be in some intellectual circles, the evidence is unequivocal: Ours is a cosmos whose laws appear finely tuned for our type of life — for advanced, carbon-based “light eaters” possessing the technologically enabling miracle of sight. Whatever the cause and whatever the ultimate explanation, nature appears to be fine-tuned to an astonishing degree for beings of our biology."
Comment: Just more evidence for fine tuning.
Privileged Planet: the Earth is in a safe place
by David Turell , Wednesday, August 19, 2020, 23:26 (1345 days ago) @ David Turell
We are on the second spiral arm two-thirds of the way out from the center, but scientists worry a supernova might have caused extinctions in the past. Without evidence so far. But it is an obvious worry:
https://www.sciencedaily.com/releases/2020/08/200818142104.htm
"Imagine reading by the light of an exploded star, brighter than a full moon -- it might be fun to think about, but this scene is the prelude to a disaster when the radiation devastates life as we know it. Killer cosmic rays from nearby supernovae could be the culprit behind at least one mass extinction event, researchers said, and finding certain radioactive isotopes in Earth's rock record could confirm this scenario.
***
"A supernova, on the other hand, delivers a one-two punch, the researchers said. The explosion immediately bathes Earth with damaging UV, X-rays and gamma rays. Later, the blast of supernova debris slams into the solar system, subjecting the planet to long-lived irradiation from cosmic rays accelerated by the supernova. The damage to Earth and its ozone layer can last for up to 100,000 years.
***
"The team said the key to proving that a supernova occurred would be to find the radioactive isotopes plutonium-244 and samarium-146 in the rocks and fossils deposited at the time of extinction. "Neither of these isotopes occurs naturally on Earth today, and the only way they can get here is via cosmic explosions," said undergraduate student and co-author Zhenghai Liu.
***
"Researchers have yet to search for Pu-244 or Sm-146 in rocks from the Devonian-Carboniferous boundary. Fields' team said its study aims to define the patterns of evidence in the geological record that would point to supernova explosions.
"'The overarching message of our study is that life on Earth does not exist in isolation," Fields said. "We are citizens of a larger cosmos, and the cosmos intervenes in our lives -- often imperceptibly, but sometimes ferociously.'" (my bold)
Comment: Perhaps it happened in the past, but no supernova candidates are close enough to us to cause trouble now.
Privileged Planet: why does Earth have so much water?
by David Turell , Wednesday, November 07, 2018, 19:43 (1996 days ago) @ David Turell
Another article on the point:
https://www.sciencedaily.com/releases/2018/11/181107130306.htm
"In the new study, researchers developed a new theoretical model of Earth's formation to explain these differences between hydrogen in Earth's oceans and at the core-mantle boundary as well as the presence of noble gases deep inside the planet.
"According to their new model, several billion years ago, large waterlogged asteroids began developing into planets while the solar nebula still swirled around the Sun. These asteroids, known as planetary embryos, collided and grew rapidly. Eventually, a collision introduced enough energy to melt the surface of the largest embryo into an ocean of magma. This largest embryo would eventually become Earth.
"Gases from the solar nebula, including hydrogen and noble gases, were drawn in by the large, magma-covered embryo to form an early atmosphere. Nebular hydrogen, which contains less deuterium and is lighter than asteroidal hydrogen, dissolved into the molten iron of the magma ocean.
"Through a process called isotopic fractionation, hydrogen was pulled towards the young Earth's center. Hydrogen, which is attracted to iron, was delivered to the core by the metal, while much of the heavier isotope, deuterium, remained in the magma which eventually cooled and became the mantle, according to the study's authors. Impacts from smaller embryos and other objects then continued to add water and overall mass until Earth reached its final size.
"This new model would leave Earth with noble gases deep inside its mantle and a lower deuterium-to-hydrogen ratio in its core than in its mantle and oceans.
The authors used the model to estimate how much hydrogen came from each source. They concluded most was asteroidal in origin, but some of Earth's water did come from the solar nebula.
"For every 100 molecules of Earth's water, there are one or two coming from solar nebula," said Jun Wu, assistant research professor in the School of Molecular Sciences and School of Earth and Space Exploration at Arizona State University and lead author of the study."
Comment: This made the Earth an ideal planet for the development of life. Certainly good planning.
Privileged Planet: water and subduction
by David Turell , Monday, November 19, 2018, 22:00 (1984 days ago) @ David Turell
The subduction zones drag lots of water into the mantle:
https://www.livescience.com/64091-earth-is-eating-its-oceans.html?utm_source=ls-newslet...
"As Earth's tectonic plates dive beneath one another, they drag three times as much water into the planet's interior as previously thought.
***
"The find has major ramifications for understanding Earth's deep water cycle, wrote marine geology and geophysics researcher Donna Shillington of the Lamont-Doherty Earth Observatory at Columbia University in an op-ed accompanying the new paper. Water beneath the surface of the Earth can contribute to the development of magma and can lubricate faults, making earthquakes more likely, wrote Shillington, who was not involved in the new research.
***
"Water is stored in the crystalline structure of minerals, Shillington wrote. The liquid gets incorporated into the Earth's crust both when brand-new, piping-hot oceanic plates form and when the same plates bend and crack as they grind under their neighbors.
***
"'Before we did this study, every researcher knew that water must be carried down by the subducting slab," Cai told Live Science. "But they just didn't know how much water."
***
"Using the measured velocities, along with the known temperatures and pressures found there, the team calculated that the subduction zones pull 3 billion teragrams of water into the crust every million years (a teragram is a billion kilograms).
"Seawater is heavy; a cube of this water 1 meter (3.3 feet) long on each side would weigh 1,024 kilograms (2,250 lbs.). But still, the amount pulled down by subduction zones is mind-boggling. It's also three times as much water as subduction zones were previously estimated to take in, Cai said.
"And that raises some questions: The water that goes down must come up, usually in the contents of volcanic eruptions. The new estimate of how much water is going down is larger than estimates of how much is being emitted by volcanos, meaning scientists are missing something in their estimates, the researchers said. There is no missing water in the oceans, Cai said. That means the amount of water dragged down into the crust and the amount spouted back out should be about equal. The fact that they aren't suggests that there's something about how water moves through the interior of Earth that scientists don't yet understand."
Comment: All of Earth's mechanisms are circular feedback loops to maintain the stability of the Earth as it evolves with additional living forms in number and variety. It all looks carefully designed to me.
Privileged Planet: life giving matter from a collision
by David Turell , Wednesday, January 23, 2019, 20:11 (1919 days ago) @ David Turell
A complex study suggests a Mars-sized body hit the Earth and supplied the volatiles needed for life to form on a rock planet initially without them:
https://phys.org/news/2019-01-planetary-collision-moon-life-earth.html
"Earth most likely received the bulk of its carbon, nitrogen and other life-essential volatile elements from the planetary collision that created the moon more than 4.4 billion years ago, according to a new study by Rice University petrologists.
" 'From the study of primitive meteorites, scientists have long known that Earth and other rocky planets in the inner solar system are volatile-depleted," said study co-author Rajdeep Dasgupta. "But the timing and mechanism of volatile delivery has been hotly debated. Ours is the first scenario that can explain the timing and delivery in a way that is consistent with all of the geochemical evidence."
***
"In a series of experiments, study lead author and graduate student Damanveer Grewal gathered evidence to test a long-standing theory that Earth's volatiles arrived from a collision with an embryonic planet that had a sulfur-rich core.
The sulfur content of the donor planet's core matters because of the puzzling array of experimental evidence about the carbon, nitrogen and sulfur that exist in all parts of the Earth other than the core.
***
"Grewal's experiments, which simulated the high pressures and temperatures during core formation, tested the idea that a sulfur-rich planetary core might exclude carbon or nitrogen, or both, leaving much larger fractions of those elements in the bulk silicate as compared to Earth. In a series of tests at a range of temperatures and pressure, Grewal examined how much carbon and nitrogen made it into the core in three scenarios: no sulfur, 10 percent sulfur and 25 percent sulfur.
"'Nitrogen was largely unaffected," he said. "It remained soluble in the alloys relative to silicates, and only began to be excluded from the core under the highest sulfur concentration."
"Carbon, by contrast, was considerably less soluble in alloys with intermediate sulfur concentrations, and sulfur-rich alloys took up about 10 times less carbon by weight than sulfur-free alloys.
***
"'What we found is that all the evidence—isotopic signatures, the carbon-nitrogen ratio and the overall amounts of carbon, nitrogen and sulfur in the bulk silicate Earth—are consistent with a moon-forming impact involving a volatile-bearing, Mars-sized planet with a sulfur-rich core," Grewal said.
***
"'This study suggests that a rocky, Earth-like planet gets more chances to acquire life-essential elements if it forms and grows from giant impacts with planets that have sampled different building blocks, perhaps from different parts of a protoplanetary disk," Dasgupta said.
"'This removes some boundary conditions," he said. "It shows that life-essential volatiles can arrive at the surface layers of a planet, even if they were produced on planetary bodies that underwent core formation under very different conditions."
"Dasgupta said it does not appear that Earth's bulk silicate, on its own, could have attained the life-essential volatile budgets that produced our biosphere, atmosphere and hydrosphere.
"That means we can broaden our search for pathways that lead to volatile elements coming together on a planet to support life as we know it.'"
Comment: The Earth is most unusual among planets studied, and might have formed this way. could this be precise control by God?
Privileged Planet: life giving matter from a collision !!
by David Turell , Wednesday, January 23, 2019, 21:22 (1919 days ago) @ David Turell
Additional thought. This is the same collision that formed our moon whose presence is vital, as shown previously, to setting up the Earth for life to appear.
Privileged Planet: fungus helped transformation of Earth
by David Turell , Wednesday, November 07, 2018, 17:56 (1996 days ago) @ David Turell
This article reveals how fungus works to control/ change the Earth's living environment:
https://cosmosmagazine.com/biology/the-secret-kingdom
"They range in size from microscopic yeast to the largest organism alive – the honey fungus Armillaria solidipes whose underground network spans 1662 football fields! After bacteria, they are the most ancient land-based life. According to the latest estimate from mycologist Mary Berbee of the University of British Columbia, they’ve been here for about a billion years, predating the first land plants by at least 500 million years.
"They eked out a living mining rocks, extracting minerals, dining on bacteria and fighting them for scarce resources. They became masters of survival.
"And then around 450 million years ago, a group of green algae splashed up on to the shoreline. Fungi extended a helping hand, sending their filaments into the plant’s tissue to provide them with a lifeline for water and minerals. The algae repaid the favour by providing sugar.
"The relationship was remarkably intimate: the fungal filaments penetrated the very cells of the plant, forming a tree-like structure that’s known as ‘arbuscular mycorrhiza’. Just how this interspecies collaboration was established has been an enduring secret of nature.
"The mystery was solved in 2015 when evolutionary microbiologist Pierre-Marc Delaux, now at Université Paul Sabatier, Toulouse, revealed that the algal ancestors of land plants, a group called ‘charophytes’, were equipped to communicate with fungi well before they encountered them. (my bold)
"Unlike other algae, these charophytes possessed a unique set of ‘signalling’ genes. This enabled them to detect and work with these co-operative fungi. Ever since, nearly every land plant has been nurtured by its symbiotic fungi.
"The greening of land set in motion a trajectory that led to the richness of life around us. Working with fungi, the first plants changed the atmosphere and sparked the evolution of terrestrial ecosystems with all their plants and animals.
"If it weren't for fungi, we wouldn’t be here.
***
"Day after day, billions of invisible fungal spores rain down upon us. Each holds the DNA blueprint for a fungus, and it can faithfully preserve that DNA for astonishing periods of time.
***
"Mushrooms may be conspicuous but they are the tip of the iceberg. The body of the fungus is a vast filamentous network of hyphae hidden below ground or inside the body of the plant or animal it is feasting on.
"Biologists traditionally divide life into single-cell or multicellular organisms. Mark Fricker, a biologist at Oxford University, says this network represents “a third mode of life”.
"Like a brain, these networks are adaptive. They respond to the environment, allowing fungi to deploy nutrients where they are most needed, explore resources, combat enemies or make urgent repairs. They are nature’s most efficient and resilient network.
***
"These bioluminescent mushrooms may look otherworldly, but the most alien feature of fungi is that they can harvest radiation to grow. Scientists first got a hint of this after the Chernobyl nuclear plant meltdown in 1986.
"In the clean up operation, they noticed dark-coloured fungi growing in the contaminated soils nearby. Their dark colour was due to melanin – the same pigment that colours human skin. Researchers thought melanin might be protecting the fungi against gamma radiation much as it protects us from UV rays.
:But according to a 2007 study by Ekaterina Dadachova and Arturo Casadevall, then at Albert Einstein College of Medicine, fungi use melanin to harvest the energy of gamma rays. In the lab, gamma rays spurred the growth of a species called Cryptococcus neoformans. But only if its melanin-producing gene was intact."
Comment: The fungus is jack of all trades, and seem to be the glue to have life change the Earth to allow the best support for life. Note my bold: the algal ancestors of land plants, a group called ‘charophytes’, were equipped to communicate with fungi well before they encountered them. It is easy for me to see the hand of God guiding the progress He wanted. Another clear example of planning for the future. There is no way it popped up by chance. Just like the Big Brain suddenly present before it was put to such advanced use as we see now. It is a pattern that cannot be denied.
Privileged Planet: bacteria may cause ore deposits
by David Turell , Saturday, January 26, 2019, 19:16 (1916 days ago) @ David Turell
A study of copper deposits suggests this is so:
https://www.sciencedaily.com/releases/2019/01/190125131014.htm
"This contribution to Geology by Fernando Tornos and colleagues tries to solve the long-standing debate on the control of microbes on secondary sulfide formation. They predict that future multidisciplinary studies will prove that microbes have a key control on the precipitation of metals in these shallow environments.
"Their case study is based on the unusual Las Cruces deposit in southwest Iberia, where a significant part of the high-grade copper ore occurs as thick, massive veins of copper sulfides. Tornos and colleagues have direct evidence that the mineralization is currently being formed there in relationship with active aquifers and in an area isolated from the surface by a thick layer of marl. Thus, the place is ideal for tracking for anaerobic microbes.
"With the help of the mining company, First Quantum, the team was able to extract pristine samples that had never been in contact with the atmosphere.
"Different microbiological techniques and detailed electron microscope studies have shown that copper sulfides are precipitating today in relationship with colonies of sulfate-reducing microbes. The nanometer-sized crystals of covellite are embedded in the polymeric compounds that encapsulate bacteria. These crystals coalesce, later forming the big veins. However, much more work is needed in order to know to which extent these processes are global and if microbes control most of the formation of the secondary copper deposits."
Comment: Another evidence that life is instrumental in forming Earth in its current form.
Privileged Planet: magnetic field history
by David Turell , Thursday, January 31, 2019, 04:37 (1912 days ago) @ David Turell
the magnetic field almost disappeared 560 million years ago just before the Cambrian Explosion started:
https://www.livescience.com/64625-earth-magnetic-field-nearly-disappeared.html?utm_sour...
"Five hundred and sixty-five million years ago, Earth's magnetic field almost disappeared.
But a geological phenomenon might have saved it, a new study suggests. Earth's then-liquid core likely began to solidify around that time, which strengthened the field, the group reported yesterday (Jan. 28) in the journal Nature Geoscience. This is important because the magnetic field protects our planet and its inhabitants from harmful radiation and solar winds — streams of plasma particles thrown our way by the sun.
"Scientists figured out what our planet's core was like back then by looking at crystals the size of grains of sand.
"They picked up samples of plagioclase and clinopyroxene — minerals that were formed 565 million years ago — in what is now eastern Quebec, Canada. These samples contain tiny magnetic needles about 50 to 100 nanometers in size, which, in molten rock, orient themselves in the direction of the magnetic field at the time.
"'Those tiny magnetic particles are ideal magnetic recorders," said co-author John Tarduno, the chair of the Earth and Environmental Sciences department and a professor at the University of Rochester in New York. "When they cool, they lock in a record of Earth's magnetic field that's maintained for billions of years."
"So, by sticking the crystals in a magnetometer, the researchers were able to figure out that the particles' charge was very low. In fact, 565 million years ago, Earth's magnetic field was over 10 times weaker than what it is today — the weakest ever documented.
"Further, the measurements showed that the frequency of north and south pole reversals was very high. All of this suggests that "the field was extremely unusual," Tarduno told Live Science. "We were at this critical point where the dynamo almost collapsed completely."
"But then the geodynamo got a kick start once more — from the very core of our planet.
"In Earth's early years, the core was all liquid. But at some point — guesses range from between 2.5 billion years to 500 million years ago — iron began to cool and freeze into a solid layer in the middle of the planet. As the inner core solidified, lighter elements like silicon, magnesium and oxygen were kicked out into the outer, liquid layer of the core, creating a movement of fluid and heat called convection. This movement of fluid in the outer core kept charged particles moving, creating an electrical current, which in turn created a magnetic field.
***
"The researchers "present intriguing paleomagnetic measurements" that suggest a weak geodynamo existed 565 million years ago, which meant that the core was fully liquid, wrote Peter Driscoll, an earth and planetary scientist at the Carnegie Institution for Science in Washington, D.C., who was not a part of the research, in a commentary that accompanied the study. If their theory holds true, "the inner core may have occurred right in the nick of time to recharge the geodynamo and save Earth's magnetic shield."
"Shortly after this time, the Cambrian explosion occurred and complex animals emerged across the planet. "One can speculate — and there have been some speculations — that a weaker magnetic field may have some relationship to these evolutionary events," Tarduno said. That is because a weaker field might allow more radiation to get through, which could cause DNA damage and higher mutation rates, which in turn, might have lead to more species evolving.
"But this is mere speculation, Tarduno said. When Earth's magnetic field weakens a bit during events such as magnetic reversals (where the north and south poles flip), for instance, there's no evidence that species are affected, he added."
Comment: Good luck or God's guiding hand? A strong magnetic field is very important protection. It helps make our privileged planet
Privileged Planet: magnetic field history II
by David Turell , Thursday, February 21, 2019, 21:36 (1890 days ago) @ David Turell
Other new commentary about the severe loss of our magnetic field about 565 million years ago:
https://www.scientificamerican.com/article/ancient-earths-weakened-magnetic-field-may-h...
"Some 565 million years ago, life on Earth dodged a bullet. The magnetosphere—the magnetic field that surrounds our planet like a protective shield—had degraded to its lowest intensity ever, according to a study published January 28 in Nature Geoscience. Stripped of this shielding, Earth could have been blasted by atmosphere-eroding outbursts from the sun, gradually losing most of its air and water until it became as dry and desolate as present-day Mars.
"Instead, deep in the planet’s interior an event was taking place that would help the magnetosphere rebound, according to the study’s authors. Earth’s liquid-iron inner core crystallized, a process geophysicists call “nucleation.” Once solid, the rotating core acted as a whirling dynamo, strengthening the protective electromagnetic bubble that wrapped around Earth, staving off planet-wide devastation. That, in turn, could have set the stage for the Cambrian explosion, an event approximately 541 million years ago in which the biosphere suddenly experienced the greatest evolutionary expansion in the planet’s history.
"The weakened magnetic field Tarduno and his colleagues discovered roughly coincided with the end-Ediacaran extinction around 542 million years ago—a mass die-off of primitive, sessile, sea-dwelling organisms that preceded the Cambrian explosion. In 2016 Carlo Doglioni, a geologist at Sapienza University of Rome, proposed the Cambrian’s profusion of new life-forms took place in part because of the magnetosphere’s growing strength. “The magnetic dipole was increasing after the Ediacaran,” Doglioni says. “We have a good, thick atmosphere that is protecting us from ionizing radiation because we have a good, strong magnetic field.” Fossil evidence suggests the organisms that endured the end-Ediacaran extinction survived by burrowing into the seafloor—a trait not shared by the immobile Ediacaran period biota that died out. As for the actual culprits in the killings, a 2016 study from Joseph Meert, a geologist at the University of Florida, blames harmful ultraviolet light and cosmic radiation that bathed the surface after passing through ancient Earth’s weakened magnetic field and thinning atmosphere. “When the shields went down, the Ediacaran organisms went extinct, clearing the ecological space for the later Cambrian explosion,” he says."
Comment: Same warning as usual. Although the Cambrian Explosion appeared, there is no evidence of what drove it.
Privileged Planet: our atmosphere like none other
by David Turell , Sunday, February 24, 2019, 04:45 (1888 days ago) @ David Turell
At least not in this solar system:
"Nowadays, Earth's atmosphere consists of approximately 80 percent nitrogen and 20 percent oxygen, Frey said. That atmosphere is also home to argon, carbon dioxide, water vapor and numerous other gases
"In short, our atmosphere is here because of gravity. When Earth formed, about 4.5 billion years ago, the molten planet barely had an atmosphere. But as the world cooled, its atmosphere formed, largely from gases spewed out of volcanoes, according to the Smithsonian Environmental Research Center (SERC). This ancient atmosphere was very different from today's; it had hydrogen sulfide, methane and 10 to 200 times as much carbon dioxide as the modern atmosphere does, according to SERC.
***
"'We believe the Earth started out with an atmosphere a bit like [that of] Venus, with nitrogen, carbon dioxide, maybe methane," said Jeremy Frey, a professor of physical chemistry at the University of Southampton in the United Kingdom. "Life then began somehow, almost certainly in the bottom of an ocean somewhere."
"After around 3 billion years, the photosynthetic system evolved, meaning that single-celled organisms used the sun's energy to turn molecules of carbon dioxide and water into sugar and oxygen gas. This dramatically increased oxygen levels, Frey told Live Science. "And that is the biggest pollution event, you might say, that life has ever done to anything, because it slowly transformed the planet," he said.
"Nowadays, Earth's atmosphere consists of approximately 80 percent nitrogen and 20 percent oxygen, Frey said. That atmosphere is also home to argon, carbon dioxide, water vapor and numerous other gases,
"It's a good thing these gases are there. Our atmosphere protects the Earth from the harsh rays of the sun and reduces temperature extremes, acting like a duvet wrapped around the planet. Meanwhile, the greenhouse effect means that energy from the sun that reaches Earth gets waylaid in the atmosphere, absorbed and released by greenhouse gases, according to the NCAR. There are several different types of greenhouse gases; the major ones are carbon dioxide, water vapor, methane and nitrous oxide. Without the greenhouse effect, Earth's temperature would be below freezing.
"Intriguingly, no other planet in the universe has an atmosphere like Earth's. Mars and Venus have atmospheres, but they cannot support life (or, at least, not Earth-like life), because they don't have enough oxygen. Indeed, Venus' atmosphere is mainly carbon dioxide with clouds of sulfuric acid, the 'air' is so thick and hot that no human could breathe there. According to NASA, the thick carbon dioxide atmosphere of Venus traps heat in a runaway greenhouse effect, making it the hottest planet in our solar system. Surface temperatures there are hot enough to melt lead.
"'The fact that Earth has an atmosphere is extremely unusual in respect of the planets in the solar system, in that it's very different from any of the other planets," Frey said. For example, the pressure of Venus is about 90 atmospheres, the equivalent to diving 3,000 feet (914 meters) beneath the ocean on Earth. "The original Russian spaceships that went there [to Venus] just recorded for a few seconds and then got crushed," Frey said. "Nobody ever really understood how hot it was."
"So, Earth's atmosphere is life — and without it, life as we know it wouldn't exist. "Earth needed the right atmosphere [for life] to get started," Frey said. "It has created that atmosphere, and it has created circumstances to live in that atmosphere. The atmosphere is a totally integral part of the biological system.'"
Comment: All of this adds up to fine tuning for the Earth to be ready to support evolved life. Note the lack of oxygen when life started. the metabolism had to be very different. Also the atmosphere may ber protective, but the magnetic field is more protective. Not by chance
Privileged Planet: when early oxygen appeared
by David Turell , Monday, February 25, 2019, 20:12 (1886 days ago) @ David Turell
Before the great oxygen event at 2.5 byo:
https://phys.org/news/2019-02-ancient-clues-earth-early-history.html
"By studying ancient rocks, researchers have determined that sometime between 2.5 and 2.3 billion years ago, Earth underwent what scientists call the "Great Oxidation Event" or "GOE" for short. O2 first accumulated in Earth's atmosphere at this time and has been present ever since.
"Through numerous studies in this field of research, however, evidence has emerged that there were minor amounts of O2 in small areas of Earth's ancient shallow oceans before the GOE.
***
"Using mass spectrometers, the team measured the thallium and molybdenum isotope compositions of the Mt. McRae Shale. This was the first time both isotope systems had been measured in the same set of shale samples. As hypothesized, a predictable thallium and molybdenum isotope pattern emerged, indicating that manganese oxide minerals were being buried in the sea floor over large regions of the ancient ocean. For this burial to occur, O2 needed to have been present all the way down to the sea floor 2.5 billion-years-ago.
"These findings improve scientists' understanding of Earth's ocean oxygenation history. Accumulation of O2 was probably not restricted to small portions of the surface ocean prior to the GOE. More likely, O2 accumulation extended over large regions of the ocean and extended far into the ocean's depths. In some of these areas, O2 accumulation seems to have even extended all the way down to the sea floor.
"'our discovery forces us to re-think the initial oxygenation of Earth," states Ostrander.
"'Many lines of evidence suggest that O2 started to accumulate in Earth's atmosphere after about 2.5 billion years ago during the GOE. However, it is now apparent that Earth's initial oxygenation is a story rooted in the ocean. O2 probably accumulated in Earth's oceans—to significant levels, according to our data—well before doing so in the atmosphere."
"'Now that we know when and where O2 began to build up, the next question is why" says ASU President's Professor and co-author Anbar. "We think that bacteria that produce O2 were thriving in the oceans long before O2 began to build up in the atmosphere. What changed to cause that build-up? That's what we're working on next.'"
Comment: life first without oxygen, then living bacteria producing oxygen so the rest of the more complex organism could evolve. A stepwise process not by chance.
Privileged Planet: strong magnetic field required
by David Turell , Friday, March 15, 2019, 18:14 (1868 days ago) @ David Turell
Survey of newly found planets finds only weak magnetic fields:
https://m.phys.org/news/2019-03-strong-planetary-magnetic-fields-earth.html
"A study by scientists at ANU on the magnetic fields of planets has found that most planets discovered in other solar systems are unlikely to be as hospitable to life as Earth.
"Plants and animals would not survive without water on Earth. The sheer strength of Earth's magnetic field helps to maintain liquid water on our blue planet's surface, thereby making it possible for life to thrive.
"Scientists from the ANU Research School of Astronomy and Astrophysics modelled the magnetic fields of exoplanets—planets beyond our solar system—and found very few have a magnetic field as strong as Earth.
"Magnetic fields appear to play an essential role in making planets habitable, so I wanted to find out how Earth's magnetic field compared to those of other potentially habitable planets," she said.
"Ms McIntyre said Earth's strong magnetic field had probably played an important role in protecting the atmosphere from the solar wind and keeping the planet wet and habitable.
"'Venus and Mars have negligible magnetic fields and do not support life, while Earth's magnetic field is relatively strong and does," she said.
"'We find most detected exoplanets have very weak magnetic fields, so this is an important factor when searching for potentially habitable planets."
***
"Co-researcher Associate Professor Michael Ireland said finding planets with strong magnetic fields was critical to the search for life elsewhere in the universe."
Comment: No surprise
Privileged Planet: tectonic plates required
by David Turell , Wednesday, April 03, 2019, 22:15 (1849 days ago) @ David Turell
It is proposed that a planet must have a surface with movable subduction floating plates, or life will not exist. So far early analysis of known planets shows none are like that :
https://www.scientificamerican.com/article/toffee-planets-hint-at-earths-cosmic-rarity/...
"That has not stopped Byrne’steam speculating on what its findings might mean for the myriad super Earths already discovered beyond our solar system. The most striking possibility is that super Earths might not be able to sustain plate tectonics—the drifting of continents and cycling of crustal rock that intimately shapes Earth. Without that process, you can say goodbye to the building of mountains, the creation of oceans and plenty of a planet’s volcanoes, and, just maybe, the evolution of complex life itself.
***
"Byrne and his colleagues’ work hinges on defining the point at which rocks deep below a planet’s surface no longer break in a mechanical way and instead begin to move like hot plastic. This point, known as the brittle-ductile transition (BDT), depends on how the pressure and temperature change with depth. For our own world’s crust, the BDT lies about 15.5 miles below the surface, although it varies quite a bit. But what about on super Earths, where greater gravitational forces would correspondingly increase pressures on rock? At what depths would BDTs emerge on such alien planets?
"The calculations revealed the BDT depths for those super Earths to be shockingly shallow, with some scarcely more than a mile beneath the surface. A nearby star, a suffocating atmosphere or an abundance of internal, radioactivity-generated heat could further bake the top of such a world, perhaps raising the BDT all the way to the surface, creating a full-blown toffee world.
***
"With that in mind, Robert Stern, a geoscientist at the University of Texas at Dallas, who was not involved in the research, says that this ambitious work deserves credit, because these sorts of numerical models will help paint a picture of what exoplanetary geology may be like. “In my lifetime, I’ve seen the solar system turn from something that belonged to astronomers to something that belonged to geologists,” he says. “We’re not there yet with exoplanets, but you can see this is a step in that direction.”
"Although incremental and provisional, the toffee worlds hypothesis could represent a sizable step indeed, as it directly addresses a question foremost in many an exoplanet-pondering geologist’s mind: Are worlds with plate tectonics common as dirt or vanishingly rare? Either way, the answer has game-changing implications.
"In order for plate tectonics to exist, a planet needs a few ingredients. Water is probably vital, because it weakens the mantle and permits chunks of the planet to slip and slide that otherwise would remain immobile. A world’s plates also must be sufficiently thick and dense to sink into the mantle—a crucial step for initiating and stabilizing the tectonic cycle over eons. Water or no, toffee worlds’ wafer-thin, brittle layers would not be able to dive deep, short-circuiting the “engine” of plate tectonics before it could even start.
"This concept reinforces the notion that plate tectonics is a rare feature in the cosmos, Stern says. After all, as far as we can presently see, Earth is the only planet where it operates.
"Aside from making toffee planets geologically dull, the absence of plate tectonics could also significantly reduce continental erosion and runoff into any oceans. This, Stern explains, would rob toffee worlds of a nutrient pump than may have given life a huge boost on ancient Earth. Plate tectonics also acts as Earth’s thermostat, keeping the planet’s temperature stable on geological timescales by buffering the levels of atmospheric greenhouse gases. Both of these tectonic side effects may be essential for the development of complex life."
Comment: All of these characteristics are well described in the three books that carefully outline how special the Earth is, and HAS TO BE, for life to appear and survive. We can only look at solar systems in this galaxy. We may well be the only Earth here, but we will never know about what might be there in other large galaxies. The question of whether we are alone in the universe can never be answered.
Privileged Planet: iron core produces protective magnetism
by David Turell , Monday, May 06, 2019, 20:53 (1816 days ago) @ David Turell
Our magnetic field protects the earth from dangerous cosmic rays. Without it there would not be life here:
https://phys.org/news/2019-05-earth-core-common-salad.html
"A Yale-led team of scientists may have found a new factor to help explain the ebb and flow of Earth's magnetic field—and it's something familiar to anyone who has made a vinaigrette for their salad.
"Earth's magnetic field, produced near the center of the planet, has long acted as a buffer from the harmful radiation of solar winds emanating from the Sun. Without that protection, life on Earth would not have had the opportunity to flourish. Yet our knowledge of Earth's magnetic field and its evolution is incomplete.
"In a new study published May 6 in the Proceedings of the National Academy of Sciences, Yale associate professor Kanani K.M. Lee and her team found that molten iron alloys containing silicon and oxygen form two distinct liquids under conditions similar to those in the Earth's core. It is a process called immiscibility.
"'We observe liquid immiscibility often in everyday life, like when oil and vinegar separate in salad dressing. It is surprising that liquid phase separation can occur when atoms are being forced very close together under the immense pressures of Earth's core," said Yale graduate student Sarah Arveson, the study's lead author.
"Immiscibility in complex molten alloys is common at atmospheric pressure and has been well documented by metallurgists and materials scientists. But studies of immiscible alloys at higher pressures have been limited to pressures found in Earth's upper mantle, located between Earth's crust and its core.
"Even deeper, 2,900 kilometers beneath the surface, is the outer core—a more than 2,000-kilometer thick layer of molten iron. It is the source of the planet's magnetic field. Although this hot liquid roils vigorously as it convects, making the outer core mostly well-mixed, it has a distinct liquid layer at the top. Seismic waves moving through the outer core travel slower in this top layer than they do in the rest of the outer core.
***
"Using laser-heated, diamond-anvil cell experiments to generate high pressures, combined with computer simulations, the Yale-led team reproduced conditions found in the outer core. They demonstrated two distinct, molten liquid layers: an oxygen-poor, iron-silicon liquid and an iron-silicon-oxygen liquid. Because the iron-silicon-oxygen layer is less dense, it rises to the top, forming an oxygen-rich layer of liquid.
"'Our study presents the first observation of immiscible molten metal alloys at such extreme conditions, hinting that immiscibility in metallic melts may be prevalent at high pressures," said Lee.
"The researchers said the findings add a new variable for understanding conditions of the early Earth, as well as how scientists interpret changes in Earth's magnetic field throughout history."
Comment: The evidence keeps piling up as to how special the Earth has to be to support life. It has to be by design.
Privileged Planet: another comment on internal importance
by David Turell , Monday, May 06, 2019, 22:59 (1816 days ago) @ David Turell
Same view presented in a different way :
https://carnegiescience.edu/node/2492
"A team of Carnegie investigators with array of expertise ranging from geochemistry to planetary science to astronomy published this week in Science an essay urging the research community to recognize the vital importance of a planet’s interior dynamics in creating an environment that’s hospitable for life.
***
"Carnegie’s Anat Shahar, Peter Driscoll, Alycia Weinberger, and George Cody argue that a true picture of planetary habitability must consider how a planet’s atmosphere is linked to and shaped by what’s happening in its interior.
"For example, on Earth, plate tectonics are crucial for maintaining a surface climate where life can thrive. What’s more, without the cycling of material between its surface and interior, the convection that drives the Earth’s magnetic field would not be possible and without a magnetic field, we would be bombarded by cosmic radiation.
***
"It all starts with the formation process. Planets are born from the rotating ring of dust and gas that surrounds a young star. The elemental building blocks from which rocky planets form—silicon, magnesium, oxygen, carbon, iron, and hydrogen—are universal. But their abundances and the heating and cooling they experience in their youth will affect their interior chemistry and, in turn, things like ocean volume and atmospheric composition.
“'One of the big questions we need to ask is whether the geologic and dynamic features that make our home planet habitable can be produced on planets with different compositions,” Driscoll explained.
"The Carnegie colleagues assert that the search for extraterrestrial life must be guided by an interdisciplinary approach that combines astronomical observations, laboratory experiments of planetary interior conditions, and mathematical modeling and simulations.
***
"In the next decade as a new generation of telescopes come online, scientists will begin to search in earnest for biosignatures in the atmospheres of rocky exoplanets. But the colleagues say that these observations must be put in the context of a larger understanding of how a planet’s total makeup and interior geochemistry determines the evolution of a stable and temperate surface where life could perhaps arise and thrive.:
“'The heart of habitability is in planetary interiors,” concluded Cody."
Comment: From what we know about how The Earth is built to support life; all the hot air hooey about exo-planets possibly being habitable requires knowing what is inside. Lots of luck! I'll take a bet that says we are alone.
Privileged Planet: new oxygen and subduction relationship
by David Turell , Friday, May 10, 2019, 21:44 (1812 days ago) @ David Turell
Further evidence about how newly arrived oxygen levels and subduction work together:
https://phys.org/news/2019-05-life-earth-affected.html
"It is well known that life on Earth and the geology of the planet are intertwined, but a new study provides fresh evidence for just how deep—literally—that connection goes. Geoscientists at Caltech and UC Berkeley have identified a chemical signature in igneous rocks recording the onset of oxygenation of Earth's deep oceans—a signal that managed to survive the furnace of the mantle. This oxygenation is of great interest, as it ushered in the modern era of high atmospheric and oceanic oxygen levels, and is believed to have allowed the diversification of life in the sea.
***
"Earth is not thought to have always had an oxygenated atmosphere and deep ocean. Rather, scientists believe, the emergence of oxygen—and with it the ability for the planet to sustain aerobic life—occurred in two steps. The first event, which took place between about 2.3 and 2.4 billion years ago, resulted in a greater than 100,000-fold increase in atmospheric O2 in the atmosphere, to about 1 percent of modern levels.
"Although it was dramatically higher than it had previously been, the atmospheric O2 concentration at this time still was too low to oxygenate the deep ocean, which is thought to have remained anoxic until around 400 to 800 million years ago. Around that time, atmospheric O2 concentrations are thought to have increased to 10 to 50 percent of modern levels. That second jump has been proposed to have allowed oxygen to circulate into the deep ocean.
***
"Their analysis revealed a distinct signature: a detectable increase in oxidized iron in bulk-rock samples between 800 and 400 million years ago, the same time interval that independent studies proposed the oxygenation of the deep ocean occurred.
***
"Stolper and Bucholz additionally compiled another proxy also thought to reflect the oxidation state of the mantle source of arc magmas. Reassuringly, this independent record yielded similar results to the iron-oxidation-state record. Based on this, the researchers propose that the oxygenation of the deep ocean impacted not only on the earth's surface and oceans but also changed the geochemistry of a major class of igneous rocks.
"This work complements earlier research by Bucholz that examines changes in the oxidation signatures of minerals in igneous rocks associated with the first oxygenation event 2.3 billion years ago. She collected sedimentary-type, or S-type, granites, which are formed during the burial and heating of sediments during the collision of two landmasses—for example, in the Himalayas, where the Indian subcontinent is colliding with Asia.
"'The granites represent melted sediments that were deposited at the surface of Earth. I wanted to test the idea that sediments might still record the first rise of oxygen on Earth, despite having been heated up and melted to create granite," she says. "And indeed, it does."
"Both studies speak to the strong connection between the geology of Earth and the life that flourishes on it, she says. "The evolution of the planet and of the life on it are intertwined. We can't understand one without understanding the other," says Bucholz."
Comment: To support life a planet must have floating plates that allow the process of subduction. Just more evidence about how special the Earth is as planet that allows life to appear.
Privileged Planet: availability of nutrients for life
by David Turell , Wednesday, May 22, 2019, 18:19 (1800 days ago) @ David Turell
A possible source for nitrogen for early life, which tends to be locked up in atmospheric gases and rocks:
https://www.sciencedaily.com/releases/2019/05/190521162432.htm
"Life on Earth relies on the availability of critical elements such as nitrogen and phosphorus. These nutrient elements are ubiquitous to all life, as they are required for the formation of DNA, the blueprints of life, and proteins, the machinery. They are originally sourced from rocks and the atmosphere, so their availability to life has fluctuated alongside significant changes in the chemistry of Earth's surface environments over geologic time.
"The research, published in Nature Geoscience, reveals how the supply of these elements directly impacted the growth of Earth's oxygen-rich atmosphere and were key to the evolution of early life on Earth.
"The most dramatic change in Earth history followed the evolution of oxygenic photosynthesis, which fundamentally transformed the planet by providing a source of carbon to the biosphere and a source of oxygen to the atmosphere, the latter culminating in the Great Oxidation Event (GOE) some 2.3 billion years ago.
"Despite the critical importance of nutrients to life, the availability of nitrogen and phosphorus in pre-GOE oceans is not well understood, particularly how the supply of these elements drove and/or responded to planetary oxygenation.
"Using samples of exceptionally well-preserved rocks that have been associated with early evidence for oxygenic photosynthesis 2.7 billion year ago, the team of researchers examined Earth's early nitrogen cycle to decipher feedbacks associated with the initial stages of planetary oxygenation.
"'There is precious little rock available from this time interval that is suitable for the type of analyses we performed. Most rocks that are this old have been deformed and heated during 2.7 billion years of plate tectonic activity, rendering the original signals of life lost," says Christopher Junium, associate professor of Earth sciences in the College of Arts and Sciences.
"The rock samples showed the first direct evidence of the build-up of a large pool of ammonium in the pre-GOE oceans. This ammonium would have provided an ample source of nitrogen to fuel the early biosphere and associated oxygen production.
***
"'Today we think of ammonium as the unpleasant odor in our cleaning supplies, but it would've served as an all-you-can-eat buffet for the first oxygen-generating organisms, a significant improvement on the dumpster scraps they relied on earlier in Earth's history."
"As well as helping scientists better understand the role of the nitrogen cycle in global oxygenation, the new findings also provide context for other nutrient feedbacks during early planetary evolution.
"'It is becoming ever more clear that the game of nutrient limitation has tipped back and forth through Earth's history as life has evolved and as conditions have changed," Junium says.
"Surprisingly, evidence for significant atmospheric oxygenation does not appear until 400 million years later, meaning that some other nutrient, such as phosphorus, must have been important in setting the evolutionary pace."
Comment: The Earth had to evolve into a planet which would easily support life. Which raises a question: how did life start about 3.8 billion years ago when nitrogen and phosphorus ere not very available?
Privileged Planet: new study of Earth's core
by David Turell , Monday, July 15, 2019, 05:23 (1747 days ago) @ David Turell
Based on isotopic findings to analyze the core as best we can:
https://cosmosmagazine.com/earth-sciences/earth-s-core-has-been-leaking-for-billions-of...
"Earth’s magnetic field protects and makes our planet habitable by stopping harmful high-energy particles from space, including from the Sun. The source of this magnetic field is the core at the centre of our planet.
"But the core is very difficult to study, partly because it starts at a depth of about 2,900 kilometres, making it too deep to sample and directly investigate.
***
"The core is the hottest part of our planet with the outer core reaching temperatures of more than 5,000℃. This has to affect the overlying mantle and it is estimated that 50% of volcanic heat comes from the core.
***
"Our findings suggest some core material does transfer into the base of these mantle plumes, and the core has been leaking this material for the past 2.5 billion years.
"We discovered this by looking at very small variations in the ratio of isotopes of the element tungsten (isotopes are basically versions of the same element that just contain different numbers of neutrons).
***
"Tungsten (chemical symbol W) as the base element has 74 protons. Tungsten has several isotopes, including 182W (with 108 neutrons) and 184W (with 110 neutrons).
"These isotopes of tungsten have potential to be the most conclusive tracers of core material, because the mantle is expected to have much higher 182W/184W ratios than the core.
"This is because of another element, Hafnium (Hf), which does not dissolve in iron-nickel alloy and is enriched in the mantle, and had a now-extinct isotope (182Hf) that decayed to 182W. This gives the mantle extra 182W relative to the tungsten in the core.
***
"Our study shows a substantial change in the 182W/184W ratio of the mantle over Earth’s lifetime. Earth’s oldest rocks have significantly higher 182W/184W than than most rocks of the modern-day Earth.
"The change in the 182W/184W ratio of the mantle indicates that tungsten from the core has been leaking into the mantle for a long time.
"Interestingly, in Earth’s oldest volcanic rocks, over a time frame of 1.8 billion years there is no significant change in the mantle’s tungsten isotopes. This indicates that from 4.3 billion to 2.7 billion years ago, little or no material from the core was transferred into the upper mantle.
"But in the subsequent 2.5 billion years, the tungsten isotope composition of the mantle has significantly changed. We infer that a change in plate tectonics, towards the end of the Archean Eon from about 2.6 billion years ago triggered large enough convective currents in the mantle to change the tungsten isotopes of all modern rocks.
"If mantle plumes are ascending from the core-mantle boundary to the surface, it follows that material from Earth’s surface must also descend into the deep mantle.
"Subduction, the term used for rocks from Earth’s surface descending into the mantle, takes oxygen-rich material from the surface into the deep mantle as an integral component of plate tectonics.
"Experiments show that increase in oxygen concentration at the core-mantle boundary could cause tungsten to separate out of the core and into the mantle. "
Comment: This shows how specially constructed our planet is with its special layers. The core creates our protective magnetic field shield. Subduction contributes to several important feed back controls to stabilized the Earth's environment.
Privileged Planet: tectonic plates started 2.5 b years a ago
by David Turell , Friday, August 09, 2019, 00:33 (1722 days ago) @ David Turell
Plate tectonics are required for complex life to exist. Our crustal movement is very old, estimated now at 2.5 byo.
https://cosmosmagazine.com/earth-sciences/the-earth-began-to-move-2-5-billion-years-ago...
"Tectonics – the movement of large surface plates across the globe – is the geological driver responsible for continental drift, the creation of mountain ranges, earthquakes, and the constant slow recycling of minerals into, and out of, the planet’s crust.
"Exactly when the phenomenon began in the 4.5 billion-year history of the Earth is a matter of considerable debate. One school of thought contends that it has been a feature of the planet’s geology almost since its formation, while another suggests that it emerged only comparatively recently, about one billion years ago.
***
"Quartzite, marble and anthracite are all examples of metamorphic rocks. By examining them it is possible to accurately measure the heat and pressure to which they were subjected, and the time period over which this occurred.
"With a large enough sample across a wide enough distribution, therefore, it is possible to estimate heat flow patterns through the ancient Earth – and heat flow is very strongly associated with plate movements.
"Holder and colleagues therefore gathered samples from 564 sites around the world. The oldest dated to about three billion years ago, but metamorphic creation kicked up in frequency about half a billion years later – indicating, the researchers conclude, the start of tectonics.
The findings – if confirmed by further analysis – are likely to force a rethink about the early history of the Earth.
“'The framework for much of our understanding of the world and its geological processes relies on plate tectonics,” says Holder.
“'Knowing when plate tectonics began and how it changed impacts that framework.'”
Comment: This fits my concept of God in control and planning ahead by preparing the Earth for the more complex life that was yet to come
Privileged Planet: measuring Earth's early crust
by David Turell , Tuesday, September 24, 2019, 19:21 (1675 days ago) @ David Turell
More than originally thought:
https://phys.org/news/2019-09-earth-crust.html
"A new international study led by a Monash geoscientist has found that more crust was formed on the early Earth than previously thought.
"The study, published today in Nature GeoScience, is part of the Monash "Pulse of the Earth' research project and has major has implications for the rate of crustal growth in Earth's earliest times and the evolution of global tectonics.
"The continental crust hosts the resources on which we depend and its evolution controls the environment in which we live.
"'Constraining the growth and destruction of the continental crust in Earth's earliest history is complicated by a severe bias in the rocks preserved at Earth's surface," said lead study author Dr. Alex McCoy-West.
"'Our study shows that up to four times the present amount of proto-crust was formed in the first billion years of Earth's history.
***
"In this latest study researchers used ultra-precise molybdenum stable isotope compositions to constrain the composition of the mantle, which has been shown to have been constant for the last three-and-a-half billion years of Earth's history.
"This mantle composition was then used to calculate through mass balance the volume of crust on the early Earth.
"'Traditional crustal growth models cannot account for a scenario in which there was more continental crust than is preserved today," Dr. McCoy-West said.
"'The unique modelling approach applied here is not pinned to the present-day crustal record and therefore has provided a new perspective on the amount of crust in Earth's earliest history," he said.
"'Our study is significant because until this period of extensive crustal growth and recycling had finished the stable continental crust required for the evolution of life would not have existed.'" (my bold)
Comment: the Earth's crust with tectonic plates moving and diving under one another creates control cycles that create a stable environment for life to exist. Clever planning on the part of God.
Privileged Planet: very early magnetic field
by David Turell , Saturday, January 25, 2020, 15:59 (1552 days ago) @ David Turell
Possibly as old as 4.2 byo in new research:
https://www.sciencemag.org/news/2020/01/new-signs-shielding-magnetic-field-found-earths...
"Earth’s earliest lands, hot and hellish, were sheltered from above. Researchers have found more evidence that our planet had a strong magnetic field 4.2 billion years ago, three-quarters of a billion years earlier than previously thought and just 350 million years after Earth formed. The field would have shielded Earth, protecting its atmosphere from being stripped away by high-energy particles from the Sun—and perhaps helping life gain a foothold. (my bold)
"With few surviving rocks to study, geologists struggle to reconstruct the time known as the Hadean, which ran from 4.55 billion years ago to 4 billion years ago. But fragmentary—and controversial—clues can be found in younger, 3-billion-year-old rocks from the Jack Hills of Western Australia. These rocks contain tiny crystals of a hardy mineral called zircon, which are chips off an even older block: 4.2-billion-year-old Hadean rocks that formed from cooling magma.
"The crystals also preserve evidence of an ancient magnetic field, according to an international team led by John Tarduno, a geophysicist at the University of Rochester. Not all researchers are convinced by the result, because it would push back the accepted birth date of Earth’s magnetic field by 750 million years. “There’s been a large research group trying to prove our results wrong,” Tarduno says. “That’s part of science.'”
Comment: This finding is not fully validated, but, noting my bold above, the early appearance of life (3.2-3.8 byo) required this protection. The Earth is a very special place. It had to be. We are here. Not by chance.
Privileged Planet: magnetic field reversals
by David Turell , Thursday, February 18, 2021, 21:09 (1162 days ago) @ David Turell
The last time was 42,000 years ago:
https://www.newscientist.com/article/2268520-earths-magnetic-field-flipping-linked-to-e...
"The most recent reversal of Earth’s magnetic field may have been as recent as 42,000 years ago, according to new analysis of fossilised tree rings. This flip of the magnetic poles would have been devastating, creating extreme weather and possibly leading to the extinction of large mammals.
"Earth’s magnetic field extends into space and is most concentrated at the north and south poles. These magnetic poles wander and occasionally reverse around every 200,000 to 300,000 years, but we have little evidence on how this impacts our planet.
"Alan Cooper at the South Australian Museum in Adelaide and his colleagues have now provided some answers. They came up with the most accurate date yet of Earth’s last magnetic field reversal called the Laschamp event, which they estimate occurred between 41,560 and 41,050 years ago and lasted less than 1000 years.
"The team calculated this estimate using radiocarbon analysis of tree rings from an ancient, fossilised kauri tree (Agathis australis) preserved in northern New Zealand wetlands.
“The tree lived right through the Laschamps and we used the shift in radiocarbon, carbon-14, in the atmosphere to detect exactly when the magnetic field collapsed,” says Cooper.
"The Earth’s magnetosphere – the region around the planet dominated by Earth’s magnetic field – weakens when the magnetic poles reverse. Cooper and his team estimate the Earth’s magnetic field was just 6 per cent of current levels during the Laschamp event.
"When the magnetic field weakens, cosmic rays enter the atmosphere and transform carbon atoms into a radioactive form called carbon-14. By measuring the levels of carbon-14 in each tree ring of the kauri tree, they were able to accurately date the Laschamp event.
"They then used climate modelling to find that several major changes coincided with the Laschamp event. The weakened magnetic field allowed more ionising radiation from solar flares and cosmic rays from space to reach Earth.
“'These damage the ozone layer and ultraviolet light comes in at very high levels,” says Cooper. This would have caused extreme weather conditions, including lightning, high temperatures and lots of sunlight – which may have been difficult for organisms to adapt to.
“'These extreme environmental changes may have caused, or at least contributed to, extinction events including those of large mammals in Australia and the Neanderthals in Europe,” says Paula Reimer at Queen’s University Belfast, who was not involved in the research. Megafauna across Australia and Tasmania – prehistoric giant mammals that existed in the Late Pleistocene – and Neanderthals in Europe went extinct around the same time as the magnetic pole reversal, 42,000 years ago."
Comment: The magnetic field protects us from most harmful rays. It is a must have. Why it flips and that lasts 1,000 years is not explained. And so it is another issue for theodicy discussion wondering if God has a reason for this phenomenon that might be required.
Privileged Planet: continental subduction allows life
by David Turell , Wednesday, February 24, 2021, 23:10 (1156 days ago) @ David Turell
A review of this vital process:
https://evolutionnews.org/2021/02/what-subduction-teaches-about-intelligent-design/
"In brief, what happens is that organisms in the oceans consume elements vital for life — carbon, phosphorous, nitrogen, sulfur — and then they die and sink to the bottom of the oceans where they get buried in sediment. If this process continues unabated then over time, ocean sediment will become a sink that accumulates life-necessary elements. Over time these elements will be segregated from the biosphere, no longer available for living organisms to use and thrive.
***
"Thankfully, there is a solution for this problem on earth, and it’s called plate tectonics — or more specifically, subduction. In plate tectonics, ocean sediment is dragged down through subduction deep into the earth on the surface of the subducting slab. When material on the slab reaches a certain depth, part of the slab melts (especially the sediments on top of the slab), and the elements travel back up to the earth through plumes of magma. There they are finally released back into earth’s surface environment through volcanoes.
***
"Our results suggest that subduction, worldwide, hosts large sources of deep H2 and abiotic CH4, potentially providing energy to the overlying subsurface biosphere in the forearc regions of convergent margins. … Geochemical data from forearc mud volcanos and hydrothermal seeps suggest that life exists as deep as 15 km below the surface at convergent margins and that the essential carbon to sustain deep microbiological habitats in the forearc of convergent plate margins is provided by the metamorphic recycling of subducting slabs. … [O]ur results suggest that high-pressure serpentinization is potentially an important source of reduced volatiles to the deep subsurface biospheres of convergent margins. Considering that low temperature and pressure serpentinization also takes place at subduction zones in the shallow forearc mantle and in obducted ophiolites, we propose that convergent margins may have represented the major source of H2 and abiotic CH4 from different depths to the surface biosphere."
Comment: A highly informative article I've greatly condensed. We can't live into the future without this process continuing. Any other planetary system must have this process for life to exist, based on our knowledge of our Earth. Design must be recognized.
Privileged Planet: continental subduction allows life
by David Turell , Tuesday, March 02, 2021, 20:07 (1150 days ago) @ David Turell
And it also creates massive Earth movements as earthquakes and sudden volcanic activity:
https://www.sciencedaily.com/releases/2021/03/210302075346.htm
"Hours before the 2018 eruption of Sierra Negra, the Galápagos Islands' largest volcano, an earthquake rumbled and raised the ground more than 6 feet in an instant. The event, which triggered the eruption, was captured in rare detail by an international team of scientists, who said it offers new insights into one of the world's most active volcanoes.
***
"For nearly two months in 2018, lava erupted from the volcano, covering about 19 square miles of Isabela Island, the largest island in the Galápagos and home to about 2,000 people and endangered animal species like the Galápagos giant tortoise.
"'The 2018 eruption of Sierra Negra was a really spectacular volcanic event, occurring in the 'living laboratory' of the Galápagos Islands," said Andrew Bell, a volcanologist at the University of Edinburgh."
***
"The scientists captured data over 13 years as the volcano's magma chamber gradually refilled following the 2005 eruption, stressing the surrounding crust and creating earthquakes. This continued until June 2018, when an earthquake occurred on the calderas fault system and triggered the subsequent eruption, the scientists said.
"'We have this story of magma coming in and stressing the system to the point of failure and the whole system draining again through the eruption of lava flows," La Femina said. "This is the first time anyone's seen that in the Galápagos to this detail. This is the first time we've had the data to say, 'okay, this is what happened here.'"
***
"Inside the Sierra Negra caldera is a "trap-door fault," which is hinged at one end while the other can be uplifted by rising magma. The scientists found the fault caused hills inside of the six-mile-wide caldera to lift vertically by more than 6 feet during the earthquake that triggered the eruption.
"Caldera resurgence, important to better understanding eruptions, had not been previously observed in such detail, the scientists reported in the journal Nature Communications.
"'Resurgence is typical of explosive calderas at volcanoes like Yellowstone, not the kind of shield volcanoes we see in the Galápagos or Hawaii," La Femina said. "This gives us the ability to look at other volcanoes in the Galápagos and say, 'well that's what could have happened to form that caldera or that resurgent ridge.''"
Comment: In order for us to live on Earth, we must put up with this dangerous process. We need all the knowledge we can use. It is all part of a pattern that our right to life comes with good and bad issues.
Privileged Planet: early Earth mostly molten
by David Turell , Friday, March 12, 2021, 22:27 (1140 days ago) @ David Turell
Latest findings using iron isotopes:
https://www.newscientist.com/article/2271279-signs-that-earth-was-once-almost-entirely-...
"Chemical signatures in 3.7-billion-year-old basalt rocks from Greenland support the long-held theory that Earth was once almost entirely molten.
"We know very little about what early Earth looked like – but one theory says that at several times it was almost entirely molten, a magma ocean. These oceans were probably caused by a series of massive impacts with other objects in our solar system that each generated enough energy to melt our planet’s interior. One of the last such collisions is thought to have formed the moon.
"Now, Helen Williams at the University of Cambridge and her colleagues have found evidence of these early magma oceans in ancient rocks.
"They collected samples of 3.7-billion-year-old basalt from the Isua supracrustal belt, an area of rocks in south-west Greenland, and measured the iron isotopes in them using chromatography and mass spectroscopy. They found unusually high levels of heavy iron isotopes – lighter ones are commonly found in younger basalt rocks.
***
"The team found that the Greenland rocks contained iron-rich minerals that hold a history of repeated crystallisation from magma oceans beginning as early as 4.1 billion years ago. Some of the minerals may have formed at least 700 kilometres below Earth’s surface.
“'The unusual ratios of iron isotopes are best explained by crystals having formed in a deep magma ocean and then being transported to the upper mantle where they melted again to form the Greenland rocks,” says Catherine McCammon at the University of Bayreuth in Germany, who wasn’t involved in the research. “Old rocks, such as the ones from Greenland, are melted reconstructions of ancient material.”
"Although this is the earliest evidence of these magma oceans, the team is confident that they existed before this. But it is difficult to find ancient rocks from Earth’s earliest days that would preserve this evidence, because any such rocks have undergone so much subsequent geological modification that their original chemical signatures are lost, says Williams."
Comment: All part of evolving a planet able to support life
Privileged Planet: deep ocean plate tectonics
by David Turell , Thursday, March 18, 2021, 19:42 (1134 days ago) @ David Turell
A new discovery based on maps of ocean plate movements:
https://www.sciencedaily.com/releases/2021/03/210317141719.htm
"First, the geological formations that are most important for its understanding lie at the bottom of the oceans. Secondly, forces controlling the processes act below the seafloor and are hence hidden from our view. Many details of plate tectonics are therefore still unclear today.
***
"It is about so-called transform faults. "These are large offsets in the mid-ocean ridges. So far, they have been assigned a purely passive role within plate tectonics. However, our analyses show that they are definitely actively involved in shaping the ocean floors," explains Prof. Ingo Grevemeyer from GEOMAR, lead author of the study.
"A look at a global overview map of the ocean floors helps to understand the study. Even at low resolution, several tens of thousands of kilometres long mid-ocean ridges can be recognised on such maps. They mark the boundaries of the Earth's plates. In between, hot material from the Earth's interior reaches the surface, cools down, forms new ocean floor and pushes the older ocean floor apart. "This is the engine that keeps the plates moving," explains Prof. Grevemeyer.
***
"The authors of the current study have now looked at available maps of 40 transform faults in all ocean basins. "In all examples, we could see that the transform valleys are significantly deeper than the adjacent fractures zones, which were previously thought to be simple continuations of the transform valleys," says co-author Prof. Colin Devey from GEOMAR. The team also detected traces of extensive magmatism at the outer corners of the intersections between transform valleys and the mid-ocean ridges.
"Using sophisticated numerical models, the team found an explanation for the phenomenon. According to this, the plate boundary along the transform fault is increasingly tilted at depth, so that shearing occurs. This causes extension of the seafloor, forming the deep transform valleys. Magmatism at the outer corners to the mid-ocean ridges then fills up the valleys, so that the fracture zones become much shallower. Oceanic crust that forms at the corners is therefore the only crust in the ocean that is formed by two-stage volcanism. What effects this has on its composition or, for example, the distribution of metals in the crust is still unknown.
"Since transform faults are a fundamental type of plate boundary and frequent phenomenon along active plate boundaries in the oceans, this new finding is an important addition to the theory of plate tectonics and thus to understanding our planet. "Actually, the observation was obvious. But there are simply not enough high-resolution maps of the seafloor yet, so no one has noticed it until now," says Prof. Grevemeyer."
Comment: There must be mechanisms that keep the plates moving, maintaining the subduction processes that cause the recycling of various elements vital to our staying alive.
Privileged Planet: short early days and oxygen levels
by David Turell , Tuesday, August 03, 2021, 15:22 (996 days ago) @ David Turell
A new theory estimating early days short length and how that may have related to staggered oxygen production from cyanobacteria mats:
https://www.sciencemag.org/news/2021/08/totally-new-idea-suggests-longer-days-early-ear...
"Now a research team has proposed a novel link between how fast our planet spun on its axis, which defines the length of a day, and the ancient production of additional oxygen. Their modeling of Earth’s early days, which incorporates evidence from microbial mats coating the bottom of a shallow, sunlit sinkhole in Lake Huron, produced a surprising conclusion: as Earth’s spin slowed, the resulting longer days could have triggered more photosynthesis from similar mats, allowing oxygen to build up in ancient seas and diffuse up into the atmosphere.
***
"Microbes that became cyanobacteria evolved the molecular machinery for photosynthesis early on, letting them convert carbon dioxide and water into sugars and oxygen. Researchers have long thought these microbes provided Earth’s initial supply of oxygen, over the eons creating an environment that favored the evolution of aerobic life in all its forms. But they always puzzled over why about a billion years passed between the first photosynthetic microbes, which fossils indicate arose about 3.5 billion years ago, and the first good geological evidence for a buildup of oxygen.
***
"Many agree that 4.5 billion years ago, a day was only about 6 hours long. By about 2.4 billion years ago, the models predict, the pull of the Moon had slowed that spin to about a 21-hour day. Earth’s rotational speed then stayed constant for about a billion years, as its gravitational pull countered the Moon’s drag. Those forces fell out of balance about 700 million years ago, because the resonance cycle between Earth and the Moon is not completely stable, and the planet’s spin slowed to its current speed, creating a 24-hour day, according to the models.
***
"...oxygen first jumped during what’s called the Great Oxygenation Event, some 2.4 billion years ago, and then again during the Neoproterozoic era, more than a billion years later. During the Paleozoic, about 400 million years ago, there was a final major increase in atmospheric oxygen.
***
"Models suggest the amount of oxygen on Earth increased in a stepwise fashion, starting with the Great Oxygenation Event (GOE) about 2.4 billion years ago, followed by a plateau for a "boring billion" years. Oxygen rose again in the Neoproterozoic Oxygenation Event (NOE) and Palaeozoic Oxidation Event (POE). Day length rose in the same stepped pattern, suggesting that the added light boosted photosynthetic microbes, fueling increases in oxygen.
"This “elegant” idea helps explain why oxygen didn’t build up in the atmosphere as soon as cyanobacteria appeared on the scene 3.5 billion years ago, says Timothy Lyons, a biogeochemist at the University of California, Riverside. Because day length was still so short back then, oxygen in the mats never had a chance to build up enough to diffuse out. “Long daytimes simply allow more oxygen to escape to the overlying waters and eventually the atmosphere,” Lyons says.
"Still, Lyons and others say, many factors likely contributed to the rise in oxygen. For example, Fischer suspects free-floating cyanobacteria, not just those in rock-affixed mats, were big players. Benjamin Mills, an Earth system modeler at the University of Leeds, thinks the release of oxygen-binding minerals by ancient volcanoes likely countered the early buildup of the gas at times and should be factored into oxygen calculations."
Comment: The Earth evolved to its present state over time. The universe evolved to its present state after the BB. Life evolved from simple Archaea. Our reality has appeared to reach its present state by processes of evolution. If God is in charge He uses evolution to reach His goals.
Privileged Planet: deep ocean plate tectonics
by David Turell , Friday, August 19, 2022, 16:23 (615 days ago) @ David Turell
Supply oxygen at deep depths:
https://phys.org/news/2022-08-giant-deep-ocean-life.html
"A previously overlooked factor—the position of continents—helps fill Earth's oceans with life-supporting oxygen. Continental movement could ultimately have the opposite effect, killing most deep ocean creatures.
***
"The water at the ocean's surface becomes colder and denser as it approaches the north or south pole, then sinks. As the water sinks, it transports oxygen pulled from Earth's atmosphere down to the ocean floor.
"Eventually, a return flow brings nutrients released from sunken organic matter back to the ocean's surface, where it fuels the growth of plankton. Both the uninterrupted supply of oxygen to lower depths and organic matter produced at the surface support an incredible diversity of fish and other animals in today's ocean.
"New findings led by researchers based at UC Riverside have found this circulation of oxygen and nutrients can end quite suddenly. Using complex computer models, the researchers investigated whether the locations of continental plates affect how the ocean moves oxygen around. To their surprise, it does.
***
"'Many millions of years ago, not so long after animal life in the ocean got started, the entire global ocean circulation seemed to periodically shut down," said Ridgwell. "We were not expecting to find that the movement of continents could cause surface waters and oxygen to stop sinking, and possibly dramatically affecting the way life evolved on Earth."
"Until now, models used to study the evolution of marine oxygen over the last 540 million years were relatively simple and did not account for ocean circulation. In these models, ocean anoxia—times when oceanic oxygen disappeared—implied a drop in atmospheric oxygen concentrations.
***
"This study used, for the first time, a model in which the ocean was represented in three dimensions, and in which ocean currents were accounted for. Results show that collapse in global water circulation lead to a stark separation between oxygen levels in the upper and lower depths.
"That separation meant the entire seafloor, except for shallow places close to the coast, entirely lost oxygen for many tens of millions of years, until about 440 million years ago at the start of the Silurian period.
"Circulation collapse would have been a death sentence for anything that could not swim closer to the surface and the life-giving oxygen still present in the atmosphere," Ridgwell said. Creatures of the deep include bizarre-looking fish, giant worms and crustaceans, squid, sponges and more.
"The paper does not address if or when Earth might expect a similar event in the future, and it is difficult to identify when a collapse might occur, or what triggers it. However, existing climate models confirm that increasing global warming will weaken ocean circulation, and some models predict an eventual collapse of the branch of circulation that starts in the North Atlantic.
***
"'You'd think the surface of the ocean, the bit you might surf or sail on, is where all the action is. But underneath, the ocean is tirelessly working away, providing vital oxygen to animals in the dark depths," Ridgwell said.
"'The ocean allows life to flourish, but it can take that life away again. Nothing rules that out as continental plates continue to move."
Comment: another way plate tectonics support life
Privileged Planet: continent formation
by David Turell , Saturday, August 20, 2022, 18:06 (614 days ago) @ David Turell
From large asteroids impacts on early Earth:
https://www.universetoday.com/157189/would-we-have-continents-without-asteroid-impacts/
"Early Earth was a wild and wooly place. In its first billion years, during a period called the Archean, our planet was still hot from its formation. Essentially, the surface was lava for millions of years. Asteroids bombarded the planet, and the place was still recovering from the impact that formed the Moon. Oceans were beginning to form as the surface solidified and water outgassed from the rock. The earliest atmosphere was actually rock vapor, followed quickly by the growth of a largely hot carbon dioxide and water vapor blanket. Earth was just starting land masses that later became continents. For decades, geologists have asked: what started continental formation?
***
"Billions of years ago, Earth, along with the other planets, was a target for incoming asteroids. The early solar system was crawling with these chunks of rock and ice. Earth itself came together as some of those objects accreted together to make a larger world. They brought substantial amounts of minerals and water to the infant planet. During Earth’s first billion years or so, the giant impacts continued through a time called the Late Heavy Bombardment. That period ended about 3.8 billion years ago, and coincides with the formation of some of the oldest remaining rocks on the planet. (my bold)
"However, a new study out of Curtin University in Australia offers one possible explanation: ancient impacts by giant asteroids. The evidence lies in zircon crystals found in one of the oldest pieces of ancient crust on Earth. They point directly to a violent period in Earth’s early history when giant meteorites crashed to the surface, planting the seeds (as it were) of the continents that grew from eruptions spurred by the impacts.
***
"The force of the collision affects both the atmosphere and the surface. The shock wave from the incoming impactor fractures and then melts the crust in a process called “shallow melting”. The illustration below shows that process. That creates crystals that are typical of impact melt. If there’s water nearby (as there almost certainly was on early Earth), then it would also play a role in crystal formation and altering rocks. Those processes are fairly typical of the aftermath of giant impacts during the first billion years of Earth’s history. If the impact is big enough, it could deliver enough punch to trigger mantle melting. The mantle is the layer just below Earth’s crust. In such an impact, lava would pour out through the fractured crust. Impacts also throw out spherules of melted material out to great distances across the surface.
***
"Given that much of Earth’s surface has changed since the Late Heavy Bombardment through erosion and inundation, the team had to look for really old rock samples dating back to that period. That’s why they went to the Pilbara Craton. It’s a pristine example of rock formed by geologic processes and shows evidence of impact-related structures and minerals created during collisions during the Late Heavy Bombardment. Those structures could well be part of the continent-forming process.
“'By examining tiny crystals of the mineral zircon in rocks from the Pilbara Craton in Western Australia, which represents Earth’s best-preserved remnant of ancient crust, we found evidence of these giant meteorite impacts,” Johnson said. “Studying the composition of oxygen isotopes in these zircon crystals revealed a ‘top-down’ process starting with the melting of rocks near the surface and progressing deeper, consistent with the geological effect of giant meteorite impacts.”
"This study of zircon crystals and other minerals is the first solid evidence pointing toward the impact-related evolution of Earth’s continents. The study of Pilbara Craton is just the first step in understanding the role of impacts in continental formation. “Data related to other areas of ancient continental crust on Earth appears to show patterns similar to those recognised in Western Australia,” said Johnson. “We would like to test our findings on these ancient rocks to see if, as we suspect, our model is more widely applicable.'”
Comment: In the evolution of the Earth continents had to appear to allow the evolution of land animals. Note my bold: during that wild period 3.8 billion years ago, life appeared!!! We should say we come from extremophiles
Privileged Planet: magnetic loss and return
by David Turell , Wednesday, September 21, 2022, 16:38 (582 days ago) @ David Turell
At a vital time with life appearing:
https://uncommondescent.com/intelligent-design/at-big-think-how-earths-magnetic-field-b...
"To piece together the history of Earth’s magnetic field, researchers use a technique called paleomagnetism, which involves studying the alignment of metal-bearing minerals in ancient rocks. When these rocks were still molten, these minerals would have acted like tiny compass needles, aligning with the magnetic fields they encountered. As the rocks solidified, these alignments froze in place, providing geologists with a snapshot of the rocks’ magnetic environments in the distant past.
"In 2019, one such study was carried out in Sept Îles, Quebec. Here, a team of researchers examined the alignment of minerals in rocks named anorthosites, which rose to Earth’s surface during the Ediacaran Period roughly 565 million years ago. Strangely, they found that these minerals were far less strongly aligned than those found in anorthosites from other periods, suggesting that Earth’s magnetic field dipped to just around 10% of its current strength during the Ediacaran.
"If this trend had continued, the future of Earth’s capacity to sustain life may have become far less certain. Yet since this unsettling result, researchers haven’t yet determined how long it took for Earth’s magnetic field to bounce back to its present-day strength.
"A rapid resurgence: Using paleomagnetism, a new team of researchers led by Tinghong Zhou at the University of Rochester, New York, may have solved this mystery. In their study, the researchers examined the alignments of minerals within slightly newer anorthosites, taken from the Wichita Mountains in Oklahoma. These rocks solidified during the Cambrian Period, around 532 million years ago, coinciding with an evolutionary explosion of complex, multicellular organisms.
"These anorthosites only formed around 30 million years after the Quebec samples — little more than a blip on geological timescales. Yet remarkably, the mineral alignments in the rocks showed that Earth’s magnetic field had largely regained its present-day strength during that time.
"Growing an inner core: To explain this rapid renewal, Zhou’s team that the Ediacaran Period must have coincided with the formation of Earth’s inner core. Before this happened, our planet’s magnetic field may have been generated by a dynamo effect within a purely molten core, which eventually began to collapse as the Earth’s interior cooled. Yet if a solid core began to form and grow over this period, it could have provided Earth’s field with a new lease of life.
"By modelling the flow of heat from the core to the mantle, the team predicted that the solid part of the core likely began to form around 550 million years ago, expanding to half its current width by roughly 450 million years ago.
"At this point, a shift in plate tectonics on Earth’s surface would have altered the structure of the mangle surrounding the core — triggering new patterns in heat flow that persist into the present day. This suggests that Earth’s inner core likely grew in two distinct stages, with a clear boundary between its inner- and outermost parts.
"A close call: The insights gathered by Zhou’s team offer a clearer picture of the dramatic events that once unfolded deep within our planet’s interior. They also provide new hints as to how Earth narrowly avoided a Mars-like fate, just as complex, multicellular life was beginning to emerge."
Comment: a clear view of this stage of evolution of the Earth, showing again God prefers to evolve His creations. Note how closely this is timed with the start of the Cambrian explosion.
Privileged Planet: meteorite's contribution
by David Turell , Friday, September 30, 2022, 20:51 (573 days ago) @ David Turell
From a meteorite study:
https://phys.org/news/2022-09-meteorites-earth-composition-collisional-erosion.html
"A team of researchers from Université Clermont Auvergne, working with a colleague from Universität Bayreuth, has found evidence that suggests the Earth's composition changed over time during its early years via collisional erosion. In their paper published in the journal Science, the group describes their study of the amounts of samarium and neodymium in meteorites and what it showed them about the processes that led to the current makeup of the Earth.
"Prior research has suggested that planets form from collisions of material in accretion disks that build up around stars during their early years. The characteristics of such collisions are believed to play a role in the resulting makeup of the resulting planets, such as their tilt angle. Prior research has also shown that Earth has a core of iron and nickel—surrounding that is a layer of iron silicate mixed in with magnesium. The top layer is described as a layer of silicate. The density of the material decreases from the core to the crust, which, Leinhardt notes, makes the crust more vulnerable during collisions.
"Prior research has also uncovered a mystery—why does the crust contain heavier minerals? A theory has suggested that they may have been pushed upward due to incompatibilities with other materials. Unfortunately, these theories do not explain why there are higher quantities of some minerals in the crust, such as neodymium, than there should be based on how much can be measured in the core.
"Three main theories have been developed to explain this anomaly. One suggests it is an illusion; there is actually more of it in the core than can be measured. Another suggests that it is because material from the accretion disk had differences in makeup. The third suggests that as heavier materials were pushed up and accumulated in the crust, some were knocked into space during new collisions.
"In this new effort, the researchers have found evidence supporting the third theory. They measured the amounts of neodymium in meteorites, assuming they were similar in makeup to Earth's building blocks, and found that up to 20% of the Earth's outer layers could have been removed by collisions, which would explain the ratio of heavy minerals such as neodymium in the crust compared to other, lighter minerals such as samarium."
Comment: this fits my theory that God evolves everything necessary. He does not instantly create, as all history shows.
Privileged Planet: meteorite's contribution of nitrogen
by David Turell , Sunday, December 03, 2023, 17:47 (144 days ago) @ David Turell
Absolutely necessary for life:
https://phys.org/news/2023-12-meteorites-source-nitrogen-early-earth.html
"Micrometeorites originating from icy celestial bodies in the outer solar system may be responsible for transporting nitrogen to the near-Earth region in the early days of our solar system. That discovery was published in Nature Astronomy by an international team of researchers, including University of Hawai'i at Mānoa scientists, led by Kyoto University.
"Nitrogen compounds, such as ammonium salts, are abundant in material born in regions far from the sun, but evidence of their transport to Earth's orbital region had been poorly understood.
***
"Like all asteroids, Ryugu is a small, rocky object that orbits the sun. The Japan Aerospace Exploration Agency's Hayabusa2 spacecraft explored Ryugu and brought material from its surface back to Earth in 2020. This intriguing asteroid is rich in carbon and has undergone significant space weathering caused by micrometeorite collisions and exposure to charged ions streaming from the sun.
***
"...Using an electron microscope, they found that the surfaces of the Ryugu samples are covered with tiny minerals composed of iron and nitrogen (iron nitride: Fe4N).
"'We proposed that tiny meteorites, called micrometeorites, containing ammonia compounds were delivered from icy celestial bodies and collided with Ryugu," said Toru Matsumoto, lead author of the study and assistant professor at Kyoto University. "The micrometeorite collisions trigger chemical reactions on magnetite and lead to the formation of the iron nitride."
"The iron nitride was observed on the surface of magnetite, which consists of iron and oxygen atoms. When magnetite is exposed to the space environment, oxygen atoms are lost from the surface by the irradiation of hydrogen ions from the sun (solar wind) and by heating through micrometeorite impact. These processes form metallic iron on the very surface of the magnetite, which readily reacts with ammonia, creating ideal conditions for synthesis of iron nitride."
Comment: a very reasonable analysis. Nitrogen is required for life to form. It conforms with my thesis God prefers to evolve His creations and a perfect Earth did evolve over time and was evolved further by the appearance of and effects of life.
Privileged Planet: early magnetic field
by David Turell , Thursday, April 25, 2024, 23:04 (1 hours, 7 minutes ago) @ David Turell
Before the iron core was fully formed:
https://www.livescience.com/planet-earth/earths-magnetic-field-formed-before-the-planet...
"Earth's magnetic field may have been similarly as strong 3.7 billion years ago as it is today, pushing the earliest date for this planetary protective bubble back 200 million years.
"The timing puts the magnetic field in play around the same time life was first emerging on Earth. The oldest fossils on the planet — bacterial mats called stromatolites — date back 3.5 billion years, with some researchers claiming to have found stromatolites as old as 3.7 billion years.
"The new study suggests that at that time, the planet had a protective magnetic bubble around it that deflected cosmic radiation and damaging charged particles from the sun.
"However, the flow of solar charged particles was much stronger at that time, said Claire Nichols, an Earth scientist at the University of Oxford and lead author of the study, which was published April 24 in the Journal of Geophysical Research. That strong "solar wind" would have stripped away the magnetosphere protecting the planet, meaning Earth was far less shielded than it is today. That finding has implications for the search for alien life.
'
"When we're looking for life on other planets, having a magnetic field is not necessarily key," Nichols told Live Science. "Because actually, with a much smaller magnetosphere, it still looks like life was able to develop."
"The hunt for extraterrestrial life is only one reason to wonder about Earth's magnetic field. Not every planet has a magnetosphere, and researchers aren't quite sure what kicked Earth's into gear. Today, the magnetic field is driven by the churning of the liquid part of the core and the transfer of heat from the solid inner core to the convective outer core as the former cools. But researchers think the core didn't solidify until about a billion years ago.
"Nichols and her team went far out of the way to seek out signs of the ancient magnetic field — 93 miles (150 kilometers) inland of Nuuk, Greenland, to a spot on the edge of the ice sheet accessible only by helicopter.
***
"Using these methods, the researchers found that 3.7 billion years ago, the magnetic field was at least 15 microtesla in strength. That's half the average strength of the magnetic field today. But it's a lower-end estimate, Nichols said, so it's possible that the field back then was around as strong as it is now.
"'Whatever is driving the magnetic field in the core was just as powerful before the core was solidified," Nichols said.
"The researchers are now interested in delving more deeply into the connections between the ancient magnetic field and Earth's atmosphere. Around 2.5 billion years ago, the atmosphere suddenly experienced a flood of oxygenation. This was partially due to the development of photosynthesis, Nichols said, but the strength of the magnetic field can affect which gases stay within the atmosphere and which ones escape into space.
"'I'm really interested to know if the magnetic field has played a role in the evolution of Earth's atmosphere over time," Nichols said.
Comment: Although this article does not worry as much about how magnetic field protects us as other articles point out, I find it amazing the Earth had an early field before the iron core was formed. Surely it was/is protective. Was God watching over?
Privileged Planet: our tilt helps life
by David Turell , Monday, July 29, 2019, 19:43 (1732 days ago) @ David Turell
New research indicates the moon was around very early after the Earth formed which helped the Earth support life:
https://phys.org/news/2019-07-moon-older-previously-believed.html
"A new study spearheaded by Earth scientists at the University of Cologne's Institute of Geology and Mineralogy has constrained the age of the Moon to approximately 50 million years after the formation of the solar system. After the formation of the solar system, 4.56 billion years ago, the Moon formed approximately 4.51 billion years ago. The new study has thus determined that the Moon is significantly older than previously believed—earlier research had estimated the Moon to have formed approximately 150 million years after solar system's formation. To achieve these results, the scientists analysed the chemical composition of a diverse range of samples collected during the Apollo missions. The study "Early Moon formation inferred from hafnium-tungsten systematics' was published in Nature Geoscience.
***
"The Moon likely formed in the aftermath of a giant collision between a Mars-sized planetary body and the early Earth. Over time, the Moon accreted from the cloud of material blasted into Earth's orbit. The newborn Moon was covered in a magma ocean, which formed different types of rocks as it cooled. "These rocks recorded information about the formation of the Moon, and can still be found today on the lunar surface," says Dr. Maxwell Thiemens, former University of Cologne researcher and lead author of the study. Dr. Peter Sprung, co-author of the study, adds: "Such observations are not possible on Earth anymore, as our planet has been geologically active over time. The Moon thus provides a unique opportunity to study planetary evolution."
"The Cologne scientists used the relationship between the rare elements hafnium, uranium and tungsten as a probe to understand the amount of melting that occurred to generate the mare basalts, i.e., the black regions on the lunar surface. Owing to an unprecedented measurement precision, the study could identify distinct trends amongst the different suites of rocks, which now allows for a better understanding of the behaviour of these key rare elements.
***
"...the study finds that the Moon already started solidifying as early as 50 million years after solar system formed. "This age information means that any giant impact had to occur before that time, which answers a fiercely debated question amongst the scientific community regarding when the Moon formed," adds Professor Dr. Carsten Münker.
Comment: Since the moon is so important to stabilizing our planet's tilt, and since we knows life appeared very early, this new finding fits the known events. Not by chance! Designed.