Care of Mr. Bad Astronomer: "First, the setup. The Deep Impact spacecraft was the one that smacked a chunk of copper into a comet so that we could see what materials were below the surface. After the impact, the spacecraft kept going (with the mission renamed EPOXI), and it’s being used to do all sorts of interesting observations.

In late May, 2008, it turned its cameras back to Earth and observed us over the course of a several hours. During this time, from EPOXI’s point of view, the Moon passed directly in front of the Earth! The images were put together (by my old boss, Don Lindler!) into, well, one of the most astonishing animations I have ever watched. Ever."