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Arches National Park Geology Tour provides an extensive, visually rich description of the geology of Arches, by Deborah Ragland, Ph.D. See our DVD collection.
This is an image of Io.
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NASA

Evolution of Io

Io is the smallest of the major Galilean satellites, with a size that could be that of the rocky core of one of the other Galilean moons. Io is heated through the process of tidal forcing, which causes the moon to be volcanic. Since the density indicates that the composition of Io is mostly rocky, there is the possibility that Io started out similar in character to the other icy moons and lost it's icy mantle over time due to tidal forcing.

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Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Amalthea

Amalthea was discovered by E Barnard in 1872. Of the 17 moons it is the 3rd closest to Jupiter, with a standoff distance of 181,300 km. Amalthea is about the size of a county or small state, and is just...more

Callisto

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...more

Evolution of Callisto

Most of the moons and planets formed by accretion of rocky material and volatiles out of the primitive solar nebula and soon thereafter they differentiated. Measurements by the Galileo spacecraft have...more

Very Large Impact Crater

Many examples of the differing types of terrain are shown in this image. In the foreground is a huge impact crater, which extends for almost an entire hemisphere on the surface. This crater may be compared...more

Surface of Callisto

The surface of Callisto is deeply pockmarked with craters. It looks to be perhaps the most severely cratered body in the solar system. There are also very large craters to be found there. The severity...more

Europa

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...more

The Atmosphere of Europa

The Galileo mission discovered an amazing thing. Europa has its own atmosphere, although it is very, very thin. This atmosphere is created when fast moving molecules in Jupiter's magnetosphere hit the...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF