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Cratering in the Solar System

Cratering in the Solar System. Lab 8. 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

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Cratering in the Solar System

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  1. Cratering in the Solar System Lab 8

  2. 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 ~1x106 yrs, large in ~100x106 yrs

  3. Impact Crater

  4. 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

  5. Asteroid Signature strip of clay that runs through rocks around the world

  6. 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

  7. isochrons Martian Lava Plains

  8. Crater Density and Size • Density • More small craters than large ones, regardless of age of surface • Size • More large craters indicates older surface

  9. 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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