SPACE.com Image Gallery: Earth and Beyond: Impact Craters

Earth and Beyond: Impact Craters

Meteor Crater, Arizona, USA

Impact craters are the most characteristic features of planetary bodies. They are geologic structures formed when a large meteoroid, asteroid or comet smashes into a planet or a satellite. Impact craters range in size from tens of meters in diameter (visible size with the current image resolution) to hundreds or thousands of kilometers. Shown above is 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 helps prove that the feature was in fact an impact crater. Click to enlarge.

NASA