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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 Tethys.
Click on image for full size

The Surface of Tethys

The surface of Tethys has many craters, which means that the surface is very old and hasn't been changed.

But there is one region of Tethys which doesn't have many craters at all. The fact that there are no craters in one region may be a sign that in the past, there was some activity on Tethys which changed the surface.

There are also several trenches across the surface. These are further signs of changes in the past.

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Tethys was discovered by G. Cassini in 1684. Tethys is the 8th closest moon to Saturn. Tethys is one of the icy moons. It is about as wide as the length of the Oregon coast. Tethys is has a surface, with...more

A Comparison of Saturn's Icy Moons, and the Earth's Moon

This is an image of the Earth's moon, shown in the lower left, with the icy moons of Saturn. The moons in order, starting from the top left are: Mimas, Enceladus, Tethys, Dione, Rhea, and Iapetus. ...more


Dione was discovered by G. Cassini in 1684. Dione is the 7th farthest moon from Saturn. It is a small icy moon, lightly cratered, with white streaks across the surface. Dione is about as wide as the Oregon...more

The Surface of Dione

The surface of Dione does not have many craters, which means that the surface has changed in the past. Instead of many craters, it has wispy white streaks like the ones on Rhea, which go for many kilometers...more

The Surface of Enceladus

The surface of Enceladus does not have many craters. Instead it has grooves similar to those found on Ganymede. These grooves extend for many kilometers over the surface. The presence of grooves indicates...more


Helene was discovered on February 29, 1980, by French scientists. Although Helene is very far away, they were able to see this small moon by using a powerful telescope and fancy camera. A few months later,...more


Hyperion was discovered by W. Bond in 1848. Hyperion is the 3rd farthest moon from Saturn. Hyperion is about the size of a large county or small state. One of the main things about Hyperion is its unusual...more


Rhea was discovered by G. Cassini in 1672. Rhea is the 5th farthest moon from Saturn. Rhea is one of the icy moons. Rhea is about as wide as the state of California is long. Rhea is has many craters and...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA