Hubble captures rare triple transit of Jupiter's moons

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Hubble captures rare triple transit of Jupiter's moons

The images on the left shows the Hubble observation at the beginning of the event. On the left is the moon Callisto and on the right, Io. The shadows from Europa, which cannot be seen in the image, Callisto, and Io are strung out from left to right. The images on the right shows the end of the event, approximately 42 minutes later. Europa has entered the frame at lower left with slower moving Callisto above and to the right of it. Meanwhile Io — which orbits significantly closer to Jupiter and so appears to move much more quickly — is approaching the eastern limb of the planet. Whilst Callisto’s shadow seems hardly to have moved Io’s has set over the planet’s eastern edge and Europa’s has risen further in the west. Image via NASA/ESA

Jupiter’s four largest moons are Io, Europa, Ganymede, and Callisto, known as the Galiliean moons, after the 17th century scientist Galileo Galilei, who discovered them. Their complete orbits around Jupiter range from two to 17 days in duration. The moons can commonly be seen transiting the face of Jupiter and casting shadows onto its layers of cloud. But seeing three of them transiting the face of Jupiter at the same time is rare, occurring only once or twice a decade.

Missing from sequence of images is the Galilean moon Ganymede which was outside Hubble’s field of view.

More info & links from EarthSky:

http://earthsky.org/space/hubble-captures-rare-triple-moon-transit-of-jupiter?utm_source=EarthSky+News&utm_campaign=52ca21b9d6-EarthSky_News&utm_medium=email&utm_term=0_c643945d79-52ca21b9d6-393525109


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