When a smaller body, such as an asteroid or comet, crashes into the surface of a larger solid body at high speed, it forms a circular depression called an impact crater. Impact craters can be found on many solar system bodies, including Mercury, the Moon, and Mars. Earth and Venus also have impact craters, but their surfaces are younger. Geological processes such as tectonics, erosion, and volcanism have continued to alter or add to their surfaces, so they show less cratering.
Surfaces that have been exposed to impact cratering for a long time preserve impacts from early in the formation of the solar system. However, surface geological processes or additional impact cratering can change the topography of the original impact craters.
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Watch this video, Planetary CSI, to see how scientists compare impact craters that have changed over time to freshly formed impact craters in order to study how landforms on Earth and other rocky planets and moons evolve.
After watching the video, describe why the Moon's surface has better preserved impact craters than Earth's surface. Write your response in the notes box below.