big enough for 1 billion Earths

Revealed: Saturn's secret 'doughnut' ring ... big enough to contain one billion Earths

By Daily Mail Reporter
Last updated at 9:44 PM on 07th October 2009

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Saturn's biggest and never-been-seen before ring has been discovered.

The 'super-sized' halo was found by Nasa's Spitzer Space Telescope. To get a sense of its size it has a vertical height which is about 20 times the diameter of the planet, which is nine times the size of our planet. Furthermore, the entire volume of the ring could hold about one billion Earths.

The bulk of the ring starts about 3.7million miles from Saturn itself and extends outward about another 7.4million miles.

With it being so huge many will ask how come it was not seen before. This is because the ring is extremely diffuse and doesn't reflect much visible light but its dusty particles, despite being very cold, shine with infrared light, or heat radiation which Spitzer is able to see.

King of the rings: This artist's illustration simulates an infrared view of the giant ring. Saturn appears as just a small dot within the band of ice and dust. The ring's diameter is equivalent to roughly 300 Saturns lined up side to side

The thin array of ice and dust particles lies at the far reaches of the Saturnian system, which contains Saturn and its 61 moons. Its orbit is tilted 27 degrees from the planet's main ring plane, Whitney Clavin from Nasa's Jet Propulsion Laboratory (JPL) which manages Spitzer.

Although the ring dust is very cold - minus 316 degrees Fahrenheit - it shines with thermal radiation.

No one had looked at its location with an infrared instrument until now, said Ms Clavin.

A paper on the discovery will be published later today by the journal Nature.

'This is one super-sized ring,' said one of the authors, Anne Verbiscer, an astronomer at the University of Virginia in Charlottesville.

Saturn's moon Phoebe orbits within the ring and is believed to be the source of the material.

The ring may also answer the riddle of another moon, Iapetus, which has a bright side and a very dark side, a pattern which resembles the yin-yang symbol. The astronomer Giovanni Cassini first spotted the moon in 1671. The dark side Cassini Regio was named in his honour.

The ring circles in the same direction as Phoebe, while Iapetus, the other rings and most of Saturn's other moons go the opposite way. Scientists think material from the outer ring moves inward and slams into Iapetus.

'Astronomers have long suspected that there is a connection between Saturn's outer moon Phoebe and the dark material on Iapetus,' said Hamilton. 'This new ring provides convincing evidence of that relationship.'

The Spitzer mission, launched in 2003, is managed by JPL in Pasadena. Spitzer is currently 66million miles from Earth in orbit around the sun.

Verbiscer's co-authors on the paper are Douglas Hamilton of the University of Maryland, College Park, and Michael Skrutskie, also of the University of Virginia.