This is an image of Europa
Click on image for full size
Courtesy of NASA
Icy Moon
Icy moons are large or small moons which are
composed mostly of ice. These moons are unlike the earth's moon, which is made of
silicate rock.
Perfect examples of icy moons are 3 of the Galilean satellites, Europa, Ganymede, and Callisto. Except maybe for Europa and Triton, these moons have no atmosphere and no magnetosphere.
Surfaces of some of these moons, particularly that of Ganymede, reveal, however, that their evolution included activity in the interior which ultimately resulted in a change in the moon's appearance. Activity in the interior could also provide an environment suitable for life.
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The Galilean satellites are the 4 major moons of Jupiter, Io, Europa, Ganymede, and Callisto. In this picture, Io, and Io’s surface, are shown on the left-most end, then Europa, and its surface, then Ganymede,
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Europa was first discovered by Galileo Galilei in 1610, making it one of the Galilean Satellites. Europa is Jupiter's 4th largest moon, 670,900 km from Jupiter. With a diameter that is about half the distance
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Callisto was first discovered by Galileo in 1610, making it one of the Galilean Satellites. Of the 60 moons it is the 8th closest to Jupiter, with a standoff distance of 1,070,000 km. It is the 2nd largest
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It is unlikely that the icy moons have an atmosphere. The reason they have no atmosphere is because they do not have enough gravity. Gravity depends upon the amount of substance (mass) contained in a body.
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Since it has been determined that the composition of the moons is mostly ice, there is probably not enough magnetic material for these to have a magnetosphere of their own. Nevertheless, because of the
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The Galileo spacecraft was only 86 miles (138 km) above the surface of Callisto when it took the pictures to the left. These are the highest resolution views ever seen of any of Jupiter's moons. You can
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The Cassini probe began its journey to Saturn on October 15, 1997. It flew by Earth in August, 1999, before heading towards the distant planet. Cassini passed Jupiter in 2000 and then burned towards its
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