A

David

Darling

secondary crater

A secondary crater is a small crater formed by ejecta thrown out of a larger impact crater. Secondary craters tend to cluster in a ring around the main crater, the greatest number lying a bit more than one crater diameter away on the Moon, but closer on Mercury because of the higher surface gravity. Ejecta falling near to the main crater tends to be moving too slowly to form craters but instead piles up as an ejecta blanket.