Astrobleme            


Scar on the surface of  a solid celestial body, caused by an impact event. These are circular in shape (or at least were at the time of their formation; tectonic activity may have altered the shape), and surrounded by rocks, minerals and structures typical of impacts. This photograph shows craters on the Moon. Astroblemes are much more visible on the Moon because of the lack of erosion, plate tectonics, and vegetation.


http://encyclopedia.fablis.com/index.php/Astronomy