Though researchers have studied the four natural satellites orbiting around Jupiter, a new set of images courtesy of the NASA/ESA Hubble Space Telescope reveals a rare new view of three of the moons in action. In a rare, and short-lived event, three of the moons moved across the striped face of the gas giant, casting shadows on the planet below.
"There are four Galilean satellites-named after the 17th century scientist Galileo Galilei who discovered them. They complete orbits around Jupiter ranging from two to seventeen days in duration" ESA spokeswoman, Georgia Blazon says. "The moons can commonly be seen transiting the face of Jupiter and casting shadows onto its layers of cloud. However, seeing three of them transiting the face of Jupiter at the same time is rare, occurring only once or twice a decade."
Using the Hubble's Wide Field Camera 3, researchers captured the event with a series of images that showed the progression of the moons across Jupiter. Callisto, Io, and Europa were all visible, though Galilean moon Ganymede remained outside of Hubble's field of view. While Callisto's shadow seemed to hardly move throughout the course of the 40-minute-observation, Io's close orbit to Jupiter allowed it to move quickly over the face of the gas giant and out of sight.
Though the distinction of the moons is often difficult to discern, researchers from the ESA and NASA used the colors of the satellites to determine which moons they were looking at.
"The moons of Jupiter have very distinctive colors" Blazon says. "The smooth icy surface of Europa is yellow-white, the volcanic sulphur surface of Io is orange and the surface of Callisto, which is one of the oldest and most cratered surfaces known in the Solar System, is a brownish color."
Want to see the moons in action? Researchers with Hubble say that you can see them with any telescope, or even with a decent pair of binoculars. But if you'd rather see check out the rare lunar event, check out the video below.
