Most prominent of the moon’s surface features are the large dark areas called maria (Latin for ‘seas’), so named because early 17th century astronomers thought they contained water. Actually the maria are circular basins filled with layers of basaltic lava, which flowed out of the moon after a large meteorite impact excavated the basin. The maria are more than 3 billion years old. In this photograph the bright white crater at bottom center is Copernicus. The circular dark region at extreme left is Mare Humorum, the ‘Sea of Moisture.’ The large dark area to the right of Copernicus is Mare Imbrium, the ‘Sea of Showers.’ The half-moon shaped feature at upper right is Sinus Iridium, the ‘Bay of Rainbows.’ North is to the right.
First quarter moon photographed at Carlisle, Massachusetts on November 7, 2000
Questar 3.5″ telescope using positive projection with 16mm Brandon eyepiece and Nikon F3, guided
Effective focal length 4025mm at f/45, 1/8 sec on Fujichrome Sensia II 400