CRATERS

Image 1: This large crater on the surface of Mars retains its original bowl shaped interior and the radial surface pattern on the ejecta. Image Credit: NASA/JPL/Arizona State University More Information: Mars Odyssey home page Image 2: The Meteor Crater in the state of Arizona was the first crater to be identified as an impact crater. Between 20,000 to 50,000 years ago, a small asteroid about 80 feet in diameter impacted the Earth and formed the crater. The crater is the best preserved crater on Earth and measures 1.2 km in diameter. For many years, scientists had denied that there were any impact craters on Earth. The origin of this crater has been a source of controversy for many years. The discovery of fragments of the Canyon Diablo meteorite help prove that the feature was in fact an impact crater. Image Credit: Public Domain/U.S. Army More Information: NASA's Near Earth Object Program