The term mare, plural maria, which in Latin means “sea,” was erroneously applied to the flat, dark plains of lower elevation on the Moon by telescopic observers of the 17th century. Actually maria are huge basins containing lava flows marked by craters, ridges, faults, and straight and meandering valleys called rilles and are devoid of water. There are about 23 major areas of this type, most of them—including the largest ones—located on the side of the Moon that always faces Earth. Eleven maria are labeled in this photo. Maria are the largest topographic features on the Moon and can be seen from Earth with the unaided eye. Together with the bright lunar highlands, they form the face of the “man in the moon.

Nikon P1000

Sharpen, contrast, labels in PS