A number of people have asked me about the little moon widget you can see at the foot of this blog, which shows the phases of the moon in real-time. In fact, the image is generated by the U.S. Navy's Time Service Department.

These lunar phase images were created by R. Schmidt from ray-traced images of the Moon. A Clementine spacecraft mosaic of the lunar surface was mapped onto a sphere, and scenes were rendered as a virtual Sun "orbited" the Moon. The depiction of lunar surface features suffers geometric distortion but the terminator is correct with respect to the spherical Moon.