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Planetary Impacts


Planetary Impacts

The last large asteroid impacts on the Moon occurred about 3.8 billion years ago and produced impact basins up to 1000 kilometers across. Large basins on other planets such as Mercury and Mars are thought to have formed at same time. Erosion, volcanism, and plate-tectonic forces erased traces of these ancient impacts on Earth. Although impacts continue to strike planets and moons throughout our solar system, the rate of impact events decreased after this time. Lunar Orbiter 4 image of the Mare Orientale basin, courtesy of NASA and the Lunar and Planetary Institute.


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