STEREO captured the transit of the Moon across the Sun.
This movie above from STEREO shows the transit of the Moon across the face of the Sun. This event could not be seen from Earth and was
visible only from the STEREO-B spacecraft (trailing behind the Earth)
in its orbit about the Sun.
The transit lasted for 12 hours. From Earth the Moon and Sun appear to be almost the same size in the sky (see SunTrek's eclipse pages) so why does the Moon look so small in this movie? It's because STEREO-B at the time was
about 1 million miles from the Earth and so was over four times further away from the
Moon than we are here on Earth even though it was still about the same distance from the Sun as Earth. As a result, the Moon appeared to be only about one quarter the size of the Sun.