The biggest of the four major moons of Jupiter — Ganymede, shown above — is three-quarters the size of Mars and larger than any other moon in our solar system. But even it is dwarfed by the planet itself, bigger than a thousand Earths. When a solar eclipse happens on Jupiter, the planet virtually subsumes the moon, which casts a small black shadow against Jupiter's surface. But on March 28th, 2004, three of those moons converged for a truly gorgeous series of shots caught by the Hubble space telescope. The video below, shot at various near-infrared wavelengths, shows a triple eclipse casting shadows on the surface of Jupiter. The shadows of Io, Ganymede, and Callisto can all be seen in the video, and a NASA image points out which is which. And a fourth major moon, Europa, remains invisible on the other side of the planet.
Video credit: NASA/ESA/University of Arizona/E. Karkoschka