Hubble Watches a Panoply of Moons Dance Around Jupiter

On Jan. 24, 2015, three of Jupiter's largest moons crossed directly in front of Jupiter's face at the same time. This is called a triple transit, and it's a relatively rare event. It was observed from many locations, but arguably the Hubble Space Telescope had the best view of all: Wow! You can see yellowish volcanic Io in the upper right, Europa on the lower left, and Callisto to its upper right.  You can see two moon shadows, too: Europa's to its upper right, and Callisto's way over on the up...