Sol System images

Quadruple Saturn Moon Transit Snapped by Hubble

By lisala on 3/28/09 5:36pm
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The Hubble Space Telescope group released an image last week that shows four of Saturn's moons in transit across the face, and rings, of Saturn. This is a fairly rare event, occurring only every fifteen years. This particular image was taken on February 24, 2009. Because the orbits of the larger Saturnian satellites are in the ring plane, or edge-on, it's an exceedingly spectacular event, and the Hubble team succeeded wildly in capturing it for us. </p.

I've linked to a small image of the moons in transit across the face of Saturn in this post; you can click it for a more detailed view, Annotated image of four of Saturn's moons in transitwith annotations. You'll see, moving from the top, Saturn's largest moon, Titan (larger even than Mercury), looking faintly orange in color because Titan's nitrogen-rich atmosphere is tinted by the side effects of sunlight on methane and nitrogen.

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Ganymede: Now You See It, Now You Don't

By lisala on 12/19/08 8:34pm
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Yesterday NASA released a nifty photo of Jupiter's largest moon, Ganymede, immediately before Ganymede seems to disappear behind Jupiter. Ganymede makes a complete orbit around Jupiter every seven days, but because Ganymede's orbit is tilted, from Earth's perspective, it looks as if Jupiter's moon passes in front of Jupiter, then disappears behind the "dark side" of the massive planet, only to reappear again later. Ganymede is not nearly as tiny as the image would suggest. In fact Ganymede is larger than the planet Mercury, but Jupiter is so huge that it dwarfs Ganymede, making the moon seem tiny even though it is the largest moon in the solar system, larger even than Earth's own satellite.

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