Often in the science of astronomy, an image will appear that makes me quietly go "wow" in awe. The Japanese Aerospace eXploration Agency, JAXA, has produced one of those images from its Kaguya (Selene) lunar orbiter.
Kaguya entered lunar orbit a month ago. Its mission is to develop the technology and to gather scientific data for future lunar exploration.
Full details of the spectacular movie of the Earth setting behind the Moon can be seen in this JAXA press release.
"Earth-sets" do not occur naturally on the Moon - the Moon always presents the same face towards the Earth, and so if you were to stand on the side of the Moon that faced the Earth, the Earth would always appear in the same area of the sky. However, Earth-rise and Earth-sets can occur on spacecraft orbiting the Moon.
The first images were taken of the lunar surface by Kaguya in early November 2007, and they can be seen in this JAXA press-release... and they are equally stunning.