The Sciences

Cassini at Saturn: Million-Ring Circus

The Cassini spacecraft investigates Saturn's rings.


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Concentric rings wind in front of Satrun's biggest moon, Titan, with tiny Janus in teh foreground. The rings are so massive that they have their own atmosphere, separate from Saturn's. Cassini found evidence of oxygen all around the icy rings.

Cassini sends radio signals through the rings back to Earth, allowing researchers to gauge the size and density of the particles. The bright purple ring, the B-ring is surprisingly dense and complex. Ring components may range from ant-size bits to moonlets the size of football fields.

Measuring 175,000 miles wide but as little as 30 feet thick, Saturn's rings contain debris of varying ages and composition, all revolving at different speeds.

The 450-mile-wide Rhea, Saturn's second-largest moon, hovers just below the rings, which are so astonishingly thin that researchers wonder how they hold together.

Titan and Dione, along with speck-sized Prometheus appear in rare alignment. Tiny so-called shepherd moons help shape the rings and prevent them from dispersing.

The 180-mile-wide Encke gap results from the tiny moon Pan ploughing a path through the rings, leaving behind scalloped edges and spiral patterns of density waves.

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