The Space & Beyond Blog
How were Saturn’s rings formed?
The mystery of Saturn’s rings
Saturn’s rings remain almost as mysterious today as they were to the Italian explorer, Galileo Galilei, when they were his first target with his new telescope 400 years ago. Scientists don’t yet know the origin of Saturn’s rings, but by using data collected by NASA’s Cassini spacecraft, astronomers have shed some light on how they formed.
The Cassini spacecraft took this stunning image of Saturn eclipsing the Sun in 2006, as the probe traveled through Saturn’s shadow. Photo: NASA/JPL
How wide are Saturn’s rings?
Saturn’s globe measures 74,900 miles (120,590km) across; its rings span 300,000 miles (483,000km). The rings are divided into groups, designated C, B, and A, working outward from the planet. Visible in a small telescope is the black band that separates rings B and A called the Cassini Division, after Giovanni Cassini, who discovered the gap in 1675. Astronomers continue to discover fainter rings. They are designated D (closest to the planet), F (a narrow feature just outside the A ring), and two distant rings called G and E.
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Saturn’s magnificent ring system appears incredibly detailed in this image created by the Cassini spacecraft. The rings comprise particles from tiny sizes up to large boulders measuring meters across. Photo: NASA/JPL
What are Saturn’s rings made of?
In April 2006, Cassini findings shed some light on what Saturn’s rings are made of. Strangely shaped gaps in some of the rings suggest elusive moonlets exist and support the notion that the rings comprise countless thousands of particles of dirty water ice ranging from microns to meters in size from an icy moon that broke up eons ago as a result of a violent collision. The scenario may be that, a few hundred million years ago, a comet or asteroid slammed into an icy moon, breaking it into pieces. Saturn’s titanic gravity then smoothed out the pieces into a flattened disk around the planet.
Data collected by Cassini suggests that Saturn’s rings are just 150 to 300 million years old. Though these results are not quite conclusive, after hundreds of years, the origin of this planet’s mysterious rings is finally beginning to come into focus.