Saturn is famous as the 'lord of the rings', even though the other three giant gas planets – Jupiter, Uranus and Neptune – also have rings. This month,
scientists announced the
discovery of a colossal ring of debris found around Saturn – it is the largest in the solar system!
Until now, the biggest known planetary rings in the solar system were Saturn's
E ring and faint, thin sheets of dust orbiting Jupiter. The newly discovered ring spans from 128 to 207 times the radius of Saturn – or farther – and is 2.4m kilometres thick.
What are Saturn's rings made of? Are they solid like the CD you used to make your model? Or are they made of many particles dancing in formation around the planet? Three robotic spacecraft from Earth have already visited Saturn – Pioneer 11, Voyager 1, and Voyager 2. They revealed many surprising things about Saturn's rings.
The source of the new ring's material seems to be Saturn's far-flung moon Phoebe. When Phoebe is hit by wayward space rocks, the impacts could generate debris that fills the rings.
When Saturn's rings were first discovered in the 17th century, drawings showed them looking like huge 'Mickey Mouse ears' on either side of the planet.
As telescopes improved, astronomers realised that they are made of millions of fragments of ice and rock. Gaps in the rings have been cleared by the gravity of nearby moons.
Like a giant compact disk, the flat rings are more than 275,000km across – wide enough to fill most of the gap between the Earth and Moon – but less than 1km thick in places. There are actually many rings – maybe 500 to 1000.
The Cassini spacecraft arrived at Saturn in July 2004, and is still in orbit. It is studying Saturn, its rings, and its moons much more thoroughly than the earlier spacecraft could.
Cassini also carried a probe, called Huygens (HOY-guns) that parachuted into the atmosphere of Saturn's giant moon Titan.
Huygens sent back amazing information and images from this strange world whose surface we have never seen.