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Published byVanessa Newman Modified over 9 years ago
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Cratering in the Solar System Lab 8
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Properties of Craters Craters formed by asteroids and comets able to penetrate the planet’s atmosphere An impactor forms a crater ~20x its own diameter After a crater is formed, it is gradually obliterated by wind or water erosion On Mars, wind erosion can obliterate a small crater in ~1x10 6 yrs, large in ~100x10 6 yrs
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Impact Crater
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Barringer Meteor Crater, Arizona (50,000 years old) Made by iron meteorite, ~30-100m in diameter, weighing ~60,000 tons, energy released by impact ~3.5 million tons of TNT
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Asteroid Signature strip of clay that runs through rocks around the world
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NEOs Pea-size meteoroids – 10/hr Walnut-size – 1/hr Grapefruit-size – 1/10 hrs Basketball-size – 1/month 50-m rock that would destroy an area the size of NJ – 1/100 yrs 1-km asteroid – 1/100,000 yrs 2-km asteroid – 1/500,000 yrs A "nemesis" parabolic comet impactor would give us a 6-month warning
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isochrons Martian Lava Plains
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Crater Density and Size Density –More small craters than large ones, regardless of age of surface Size –More large craters indicates older surface
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Ages Mercury 4.6 billion years old Mars 4.6 billion years old Earth 4.5 billion years old Moon 4.5 billion years old http://coolcosmos.ipac.caltech.edu/cosmic _kids/AskKids/index.shtml
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