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With Explore the Planets, investigate the planets, their moons, and understand the processes that shape them. By G. Jeffrey Taylor, Ph.D. See our DVD collection.
The Phoebe ring is too dim to be seen. It was detected at infrared wavelengths by the Spitzer space telescope. This image is an artist's depiction. Note that Saturn and its other, closer rings, shown in an inset, are just a small dot at the size scale of the Phoebe ring.
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Image courtesy of NASA/JPL/Space Science Institute.

The Phoebe Ring Around Saturn

The Phoebe Ring is much larger than Saturn's other rings. Saturn's main ring system starts a few thousand kilometers above the top of Saturn's atmosphere and extends outward a few hundred thousand kilometers. The Phoebe Ring is roughly 100 times larger than the main ring system; it extends from about 6 million to about 12 million km above Saturn's cloudtops.

Saturn's moon Phoebe orbits within this ring and appears to be the source of the material that makes up the ring. The Phoebe Ring is very tenuous and has not yet been seen with visible light. The infrared Spitzer Space Telescope was able to detect the faint Phoebe Ring in IR images. The ring is composed of tiny flecks of ice and dust, probably knocked loose from Phoebe's surface by meteorite impacts over many millennia.

Saturn's main ring system lies within the planet's equatorial plane. The Phoebe Ring is tilted 27. Part of the Phoebe Ring crosses the orbit of another moon of Saturn, Iapetus. The surface of Iapetus is odd; parts of it are very bright, while other areas are quite dark. Perhaps icy Iapetus is being splattered with dark particles from the Phoebe Ring. Phoebe itself has one of the darkest surfaces in our Solar System.

The ring was discovered by Anne Verbiscer and Michael Skrutskie of the University of Virginia and Douglas Hamilton of the University of Maryland. They announced their discovery on October 6, 2009.

Last modified October 9, 2009 by Randy Russell.

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