What can scientists determine from the number of craters on a body?
1 Answer
Intensity of bombardment, presence of an atmosphere, and relative information on timing of bombardment events.
Explanation:
Most of the heavy bombardment of the planets in our solar system happened about 4.3 billion years ago when the system was still in the process of settling down. Stray bits and scraps that had not contributed to forming planets, were still crashing around.
A heavily cratered planet tells us that it was subjected to a heavy bombardment at some point. Plus, if we can still see the craters 4 billion or so years later, it suggests the body does not have an atmosphere or water and that active erosion/weathering is not going on - otherwise, like on Earth, the evidence would be gone.
Overlapping craters can also tell us that there was at least two episodes of bombardment, but this is only a relative dating technique, not absolute. See pic from the moon. This pic suggests that the little crater was from a separate and later bombardment event than the big one.
