 For instance, a projectile that strikes the moon will probably hit intact; whereas if it strikes the earth, it will be slowed and heated by atmospheric entry, possibly breaking up.In that case, the smaller chunks, now separated from the large impacting body, may impact the surface of the planet in the region outside the primary crater, which is where many secondary craters appear following primary surface impact.For primary impacts, based on geometry, the most probable impact angle is 45° between two objects, and the distribution falls off rapidly outside of the range 30° – 60°.