lunar features
Aspect of the Moon determined by past volcanic activity, meteorite impact and soil fractures.
mountain range 
Vestiges of the walls of a once-large crater; semicircular in shape, it can span hundreds of miles.
sea 
Designates the vast plains of hardened lava forming the dark regions; younger than the highlands, these cover 15% of the surface.
highland 
Designates bright regions riddled with craters; these oldest regions cover 85% of the surface.
crater ray 
Band that radiates from a young crater, the result of matter ejected during a meteorite impact.
cirque 
Vast crater characterized by remarkable relief; varies between 12 and 120 mi in diameter.