Share PowerPoint. Anywhere!
Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

imp cra

Uploaded from authorPOINT Lite
Download as Download Not Available PPT
Presentation Description

No description available

Like authorSTREAM?


You can vote once a day till December
10th, Vote Now!
Views: 87
Like it  ( Likes) Dislike it  ( Dislikes)
Added: January 16, 2008 This presentation is Public
Presentation Category :Education
Presentation StatisticsNew!
Views on authorSTREAM: 87
Presentation Transcript

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…