VIDEO: Hubble’s Hat Trick

Astronomers routinely see the moons of other planets crossing in front of the worlds they orbit.  But only once or twice a decade do they see three of Jupiter’s largest moons—Europa, Callisto and Io—“transiting” at the same time.  The Hubble Space Telescope captured such a view on January 24—and caught a couple of smaller moons in the process. Click here for a larger version of the image.