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Impact Craters: 

Impact Craters

What are craters?: 

What are craters? Craters are bowl-shaped ground depressions created by: 1) volcanic eruptions, 2) bomb explosions, or 3) falling debris from space (impactors). Candidates for impactors are asteroids, comets, and meteoroids.

Impactors: 

Impactors Asteroids: rocky leftover planetesimals of the inner solar system consisting of rocky and metallic substances. Ida and its satellite, Dactyl

Impactors: 

Impactors Most asteroids originate from the asteroid belt located between Mars and Jupiter.

Impactors: 

Impactors Comets: icy leftover planetesimals of the outer solar system. They are “dirty space snowballs” consisting of ice, gases, dust, and a rocky core. Comet Hyakutake

Impactors: 

Impactors Short period comets come from the Kuiper Belt. Long period comets come from the Oort Cloud.

Impactors: 

Impactors Meteoroid: small debris left from comets or asteroid collisions. Meteor: a meteoroid moving through the Earth’s atmosphere (a.k.a. a “shooting” or “falling” star). Meteorite: a meteoroid that has fallen to the Earth’s surface.

Barringer Crater: 

Barringer Crater Approximately 1.2 km (0.75 mi.) wide and 200 m (650 ft.) deep. Created about 50,000 years ago by a 50 m (150 ft.) meteorite.

Barringer Crater: 

Barringer Crater The impact gerated a blast of 20,000,000 tons of TNT upon impact.

Chicxulub Crater: 

Chicxulub Crater Located off the coast of Mexico’s Yucatan Peninsula. At least 180 km (108 mi.) across and 45 km (27 mi.) deep.

Chicxulub Crater: 

Chicxulub Crater Created 65 million years ago by a 10-km (6 mi.) impactor.

Extra-terrestial Craters: 

Extra-terrestial Craters Our moon was probably created when a Mars-size object collide with the forming Earth billions of years ago. Callisto, a moon of Jupiter, is the most cratered body in our solar system.

Impact frequency: 

Impact frequency

Collisions: good or bad?: 

Collisions: good or bad? Good: early rain of rock and ice brought materials for the atmospheres, oceans, and polar caps to form. Could have also brought progenitors of life (amino acid compounds). Bad: any impact with a fairly large impactor today would be catastrophic. Thus…