How does a planets atmosphere affect its number of impact craters?
An atmosphere will lessen both the amount and size of impact craters by burning meteoroids so they get smaller or even disappear entirely. If there is no atmosphere, the object will simply hit the planet or moon with no reduction in its size. Earth’s atmosphere does this because the air molecules create friction when the meteoroid passes through it. The friction is hot enough to burn the meteoroid up entirely or at least down in size. An atmosphere means fewer and smaller meteoroids. (When a meteoroid does make it to the ground, it then is called a meteorite.
