Hubble Space Telescope Captures Images of Rare Jupiter Triple-Moon

— -- The Hubble space telescope captured three of Jupiter's largest moons in transit at the same time across the banded face of the planet.

The sharp photos released today by NASA were taken on January 24 with the Hubble telescope. They show three of Jupiter's biggest moons, Europa, Callisto and Io, moving together across the face of the gas-giant planet.

The three moons are known as Galilean moons since they were discovered by the scientist during the 17th century. With orbits ranging from two to 17 days, it's common for at least one of the moons to be seen orbiting the Jupiter. However, the convergence of the three is an occurrence so rare that NASA said it happens only once or twice per decade.

The fourth Galilean moon, Ganymede, was outside the Hubble's view and was not part of the celestial sight.

Of Jupiter's moons, the most interest has centered around Europa, which is thought to have elements that could make it hospitable to multi-cellular life.

Getting a closer look could soon be a reality. The $18.5 billion NASA budget recently proposed by the White House for next year includes money earmarked "for Planetary Science including formulation of a mission to Jupiter’s moon Europa."

Under its icy shell, Europa is believed to have an interior ocean that could perhaps be 10 times deeper than those on Earth, and include two to three times the volume of all liquid water on our planet.