Terminator Moon

Explanation: What's different about this Moon? It's the terminator s. In the featured image, you can't directly see any terminator -- the line that divides the light of day from the dark of night. That's because the image is a digital composite of 29 near-terminator lunar strips. Terminator regions show the longest and most prominent shadow s -- shadows which, by their contrast and length, allow a flat photograph to appear three-dimensional. The original images and data were taken near the Moon by NASA's Lunar Reconnaissance Orbiter . Many of the Moon's craters stand out because of the shadow s they all cast to the right. The image shows in graphic detail that the darker regions known as maria are not just darker than the rest of the Moon -- they are flatter.

Dial-A-Moon: Find the phase of the Moon on your birthday.