The Science of The Callisto Incident
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Europa is the smallest of the 4 Galilean moons, and the second-closest to Jupiter. Still it's the sixth largest moon in the solar system, about the size of Earth's moon! Gravity on the surface is 0.137 g (1g=Earth). Average distance from Jupiter is 670,000km, or 9.5 Jupiter Radii. One orbit of Jupiter takes 3.55 days, and the same face of Europa is always pointing toward Jupiter (same is true of all Jupiter's moons). Europa's orbit is not a perfect circle, so there's some tidal heating like on Io.
(Original Caption for above Picture): This image shows two views of the trailing hemisphere of Jupiter's ice-covered satellite, Europa. The left image shows the approximate natural color appearance of Europa. The image on the right is a false-color composite version combining violet, green and infrared images to enhance color differences in the predominantly water-ice crust of Europa. Dark brown areas represent rocky material derived from the interior, implanted by impact, or from a combination of interior and exterior sources. Bright plains in the polar areas (top and bottom) are shown in tones of blue to distinguish possibly coarse-grained ice (dark blue) from fine-grained ice (light blue). Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long. The bright feature containing a central dark spot in the lower third of the image is a young impact crater some 50 kilometers (31 miles) in diameter. This crater has been provisionally named 'Pwyll' for the Celtic god of the underworld. More Europa Info can be found here.