Hubble captures rare triple-moon conjunction

This video shows a rare look at three of Jupiter's largest moons parading across the banded face of the gas-giant planet: Europa, Callisto, and Io. They were photographed by NASA's Hubble Space Telescope on January 24, 2015. These large moons can commonly be seen transiting the face of Jupiter and casting shadows onto its cloud tops. However, seeing three moons transiting the face of Jupiter at the same time is rare. This time-lapse video, which compresses 42 minutes' duration, shows the progression of the moons Io (right), Callisto (center), and Europa (left). The moons' orbital velocities are proportionally slower with increasing distance from the planet.

Credit: NASA, ESA, and the Hubble Heritage Team and G. Bacon (STScI/AURA)