Saturn

This image, provided by NASA May 31, 2007, was taken as the Cassini spacecraft flew over the unlit side of Saturn, capturing Saturn's glow. Saturn's shimmering rings may be as old as the solar system, scientists said Dec. 12, 2007, debunking earlier theories that the rings were formed during the dinosaur age.

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Geyser-like eruptions of ice particles and water vapor shoot out from the south pole of Saturn's moon, Enceladus, in this image provided in March, 2008, by NASA. Three years after gigantic geysers were spied on an icy Saturn moon, the international Cassini spacecraft is poised to plunge through the fringes of the mysterious plumes to learn how they formed.

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This false-color image of Saturn's main rings was made by combining data from multiple star occultations using the Cassini spacecraft ultraviolet imaging spectrograph. During occultations, scientists observe the brightness of a star as the rings pass in front of the star. This provides a measurement of the amount of ring material between the spacecraft and the star. Cassini has given scientists the most detailed view yet of Saturn's densely packed B ring. Cassini found that this part of the rings is densely packed with clumps, called self-gravity wakes, separated by nearly empty gaps. These clumps in Saturn's B ring are neatly organized and constantly colliding, which surprised scientists. Colors in this image indicate the orientation of clumps, and brightness indicates the density of ring particles. The formation of wakes is strongest in the bluer regions, where ring particles clump together in tilted wakes. Particles in the central yellow regions are too densely packed for any starlight to pass through.

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This image of Saturn shows the planet floating obliquely as one of its gravity-bound companions, Dione, hangs in the distance. The darkened rings seem to nearly touch their shadowy reverse images on the planet below. This view looks toward the unlit side of the rings from about 9 degrees above the ring plane. The rings glow feebly in the scattered light that filters through them. Dione is 700 miles across. The image was taken in visible light with the Cassini spacecraft wide-angle camera Feb. 4, 2007, at a distance of approximately 800,000 miles from Saturn.

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A true color view from the Cassini spacecraft taken Jan. 18, 2005 and released by NASA/JPL/Space Science Institute, shows the moon, Mimas, as it drifts along in its orbit against the azure backdrop of Saturn's northern latitudes. The long, dark lines on the atmosphere are shadows cast by the planet's rings. Saturn's northern hemisphere is presently relatively cloud-free, and rays of sunlight take a long path through the atmosphere. This results in sunlight being scattered at shorter (bluer) wavelengths, thus giving the northernmost latitudes their bluish appearance at visible wavelengths.

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Saturn's moon Titan, left, casts it's shadow on Saturn, with it's rings on edge to the Earth and the Sun. These edge-on alignments of the rings occur roughly once every 15 years. Astronomers have woven NASA Hubble Space Telescope images of Saturn, its rings, and several of its moons into three movies. Each movie highlights unique times in the planet's 30-year waltz around the Sun.

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Saturn's moons -- Janus, top, and Prometheus, along the ringplane of Saturn -- were photographed in visible light with the Cassini spacecraft narrow-angle camera on April 29, 2006 at a distance of approximately 135,000 miles from Janus and 236,000 miles from Prometheus.

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The Cassini spacecraft made this view of Saturn enveloped by the full splendor of its rings on Jan. 19, 2007. Taking in the rings in their entirety was the focus of this particular imaging sequence. Therefore, the camera exposure times were just right to capture the dark-side of its rings, but longer than that required to properly expose the globe of sunlit Saturn. Consequently, the sunlit half of the planet is overexposed. Between the light of day and the dark of night, there is a strip of twilight on the globe where colorful details in the atmosphere can be seen. Bright clouds dot the bluish-gray northern polar region here. In the south, the planet's night side glows golden in reflected light from the rings' sunlit face. Saturn's shadow stretches completely across the rings. The view is a mosaic of 36 images -- 12 separate sets of red, green and blue images -- taken over the course of about 2.5 hours, as Cassini scanned across the entire main ring system.

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This photo, released by NASA on March 9, 2006, shows the surface of Saturn's moon Enceladus as seen from the Cassini spacecraft. Three years after Yellowstone-like geysers were spied on the icy Saturn moon, the international spacecraft is poised to plunge through the mysterious plumes to learn whether the environment can support life.

NASA / AP

In this image released by NASA back on Dec. 16, 2004, Saturn's moon Dione is shown against the globe of Saturn as Cassini approached the icy moon for a close rendezvous on Dec. 14, 2004. The images used to create this view were obtained with the Cassini spacecraft wide-angle camera at a distance of approximately 375,000 miles from Dione.

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