Secondary craters are impact craters formed by ejected debris from a primary impact event. When a large meteorite or asteroid collides with a planetary surface, it creates a crater and ejects rocks and debris at high velocities. These secondary fragments can then impact the surface at a distance from the primary crater, creating secondary craters. These secondary craters are often smaller and shallower than the primary crater, and their distribution and size can provide valuable information about the impact event and the geological history of the planetary surface. Studying secondary craters can help researchers understand the processes of impact cratering and the effects of asteroid and comet impacts on planetary surfaces.