Privileged Planet: we have fine tuned amount of carbon (Introduction)

by David Turell , Tuesday, April 06, 2021, 21:08 (1328 days ago) @ David Turell

Just analyzed:

https://www.sciencedaily.com/releases/2021/04/210402141742.htm

"The first study, led by U-M researcher Jie (Jackie) Li and published in Science Advances, finds that most of the carbon on Earth was likely delivered from the interstellar medium, the material that exists in space between stars in a galaxy. This likely happened well after the protoplanetary disk, the cloud of dust and gas that circled our young sun and contained the building blocks of the planets, formed and warmed up.

"Carbon was also likely sequestered into solids within one million years of the sun's birth -- which means that carbon, the backbone of life on earth, survived an interstellar journey to our planet.

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"A planet's carbon must exist in the right proportion to support life as we know it. Too much carbon, and the Earth's atmosphere would be like Venus, trapping heat from the sun and maintaining a temperature of about 880 degrees Fahrenheit. Too little carbon, and Earth would resemble Mars: an inhospitable place unable to support water-based life, with temperatures around minus 60.

"In a second study by the same group of authors, but led by Hirschmann of the University of Minnesota, the researchers looked at how carbon is processed when the small precursors of planets, known as planetesimals, retain carbon during their early formation. By examining the metallic cores of these bodies, now preserved as iron meteorites, they found that during this key step of planetary origin, much of the carbon must be lost as the planetesimals melt, form cores and lose gas. This upends previous thinking, Hirschmann says.

"'Most models have the carbon and other life-essential materials such as water and nitrogen going from the nebula into primitive rocky bodies, and these are then delivered to growing planets such as Earth or Mars," said Hirschmann, professor of earth and environmental sciences. "But this skips a key step, in which the planetesimals lose much of their carbon before they accrete to the planets."

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"'The planet needs carbon to regulate its climate and allow life to exist, but it's a very delicate thing," Bergin said. "You don't want to have too little, but you don't want to have too much.'"

Comment: More fine tuning to add many factors that are just perfect for life to start and remain.