Watching killer asteroids (Introduction)
by David Turell 
, Wednesday, January 23, 2013, 20:43 (4323 days ago)
We need to. Bruce Willis won't always be available:-http://blogs.scientificamerican.com/observations/2013/01/22/asteroid-hunter-gives-an-update-on-the-threat-of-near-earth-objects/?WT_mc_id=SA_DD_20130123
Watching killer asteroids
by David Turell , Tuesday, February 12, 2013, 17:55 (4303 days ago) @ David Turell
More on the Feb. 15th asteroid near miss. not to worry:-http://earthsky.org/space/asteroid-2012-da14-will-pass-very-close-to-earth-in-2013
Watching killer asteroids
by David Turell , Friday, February 15, 2013, 15:34 (4300 days ago) @ David Turell
edited by unknown, Friday, February 15, 2013, 15:43
And a large meteorite hits Russia yesterday:-http://www.newscientist.com/article/dn23178-russian-meteor-will-teach-us-about-future-bigger-hits.html-http://phys.org/news/2013-02-meteor-shower-panic-central-russia.html-And a huge asteroid hit about 350 mya in Australia:-http://phys.org/news/2013-02-world-largest-asteroid-impact-zone.html
Watching killer asteroids; recents finds
by David Turell , Monday, January 19, 2015, 14:07 (3597 days ago) @ David Turell
Still a scary problem. At least over 1,500 are nearby, some crossing our orbit, others outside:-http://wattsupwiththat.com/2015/01/19/bigger-problems-than-global-warming-nasa-discovers-8-new-dangerous-near-earth-asteroids/-"YP139 has a “H” value of 21.6, which corresponds to a possible diameter of 130 - 300 metres.-"To put this into perspective, the Chelyabinsk meteor which caused a 500 kiloton explosion over Russia in 2013 was estimated to be around 20 metres in diameter. http://en.wikipedia.org/wiki/Chelyabinsk_meteor A 300 metre object has the potential to cause (300 ^ 3 / 20 ^ 3) * 500 kilotons = 1.6 Gigaton explosion. An explosion of this magnitude, especially an ocean strike, could create gigantic Tsunamis, and would severely disrupt the global climate for several years, possibly longer.-"Its nice to know that NASA occasionally takes a break from climate bothering, long enough to do something space related, but I'm mildly horrified that a project this important appears to be so far down the list of priorities, that the project was mothballed for a year while the survey satellite stood waiting for a refuel. Granted that a major Asteroid strike is a low probability event, but the consequences are potentially catastrophic - a big ocean strike could kill millions, maybe even billions of people.-"As the Chelyabinsk wakeup call demonstrated, the risk of a damaging meteor impact is not a possibility which should be neglected."-From NASA:-http://neo.jpl.nasa.gov/neo/groups.html
Watching killer asteroids; recents finds
by David Turell , Sunday, October 25, 2015, 12:35 (3318 days ago) @ David Turell
Another close fly-by coming this October, 1.3 lunar distances close, in five days:-http://wattsupwiththat.com/2015/10/23/city-busting-earth-grazer-asteroid-imminent-near-miss-just-discovered-2-weeks-ago/-"Yet another indication that Asteroids are a far more serious threat than climate change. NASA scientists have just in the last few weeks detected a previously unknown Asteroid, a quarter of a mile across, approaching at an unusually high speed of 35km / second, which is due to narrowly miss the Earth on 31st October this year. The asteroid will only approach within 1.3 lunar distances of Earth, so this particular body poses no threat - but in terms of the scale of the solar system, this upcoming event counts as a very near miss. This asteroid is a wakeup call, a reminder of just how vulnerable we are to catastrophic impacts, and how little warning we might receive if such a threat were detected.-***-"How likely is such an impact? Thankfully really large impact events are very infrequent, though multi kiloton impact events are common - at least 26 such events have been detected since 2001, mostly in uninhabited regions. But there is no upper limit to the size of an impact event, and as this recent imminent near miss demonstrates, a serious threat could arise with very little warming.-"What could be done to mitigate asteroid impact risk? At the very least better monitoring systems could be deployed, to try to provide at least some warning. Chelyabinsk received no warning when it was struck by a meteor. This asteroid was only detected a few weeks ago.-"With enough warning people could be evacuated from likely impact zones. Even very large threats could potentially be addressed, if there was enough time to prepare.-"In my opinion it is obscene that the world is spending countless billions chasing the imaginary perils of the climate dragon, while neglecting a far more serious threat to people's lives."-Comment: Now here is a real project for the feckless UN.
Watching killer asteroids; recent finds
by David Turell , Sunday, November 15, 2020, 22:12 (1470 days ago) @ David Turell
A new possible menace:
https://phys.org/news/2020-11-apophis-asteroid-earth-thought.html
"The asteroid Apophis was first spotted by astronomers back in 2004. Shortly thereafter, researchers worked out its orbital path and found that the 340-meter-wide asteroid would pass near to the Earth in 2029, 2036 and again in 2068. More study showed that there was little chance of the asteroid striking Earth; thus, it was discounted as a threat. More recently, Tholen and his team noted that earlier researchers had not accounted for the Yarkovsky effect by which rays from the sun strikes one side of an asteroid. As the heat radiates away from the asteroid, a small amount of energy pushes back against the asteroid, forcing it to turn slightly. Tholen and his team calculated that the Yarkovsky effect is pushing Apophis to one side enough to force it to drift by approximately 170 meters a year. They next applied that bit of knowledge to the math describing Apophis's orbit and found that the drift is changing the course of the asteroid in a way that will bring it closer to Earth. He notes that thus far, there is no indication that the asteroid will strike the Earth in 2029 and 2036, but 2068 might be another matter. He suggests that astronomers will have to keep an eye on Apophis as its rendezvous date approaches.
"As news of a possible threat from Apophis arises, others have pointed out that the human race has made strides in protecting the planet from asteroid strikes. NASA's DART mission, for example, scheduled for 2022, will involve sending a spacecraft to an asteroid called Didymos and using it to alter the path of Dimorphos, one of its moons. Tholen noted during his talk that study of Apophis when it passes by in 2029 should give scientists a much better idea of whether or not it poses an actual threat in 2068." (my bold)
Comment: We've made real advances since we started to worry about asteroids striking the Earth, as shown in my bold. In the theodicy discussion this evil or danger was not noted but it is another issue for that topic. My only answer it that the solar system may have had to have those a steroid bodies present in its formation. At least we know different ways of moving them from their orbit, if dangerous.