Washington, Mar 9 (UNI) Like Saturn its moon Rhea too have rings around it, claims new findings by NASA.
NASA's Cassini spacecraft has evidence of material orbiting Rhea, Saturn's second largest moon. This is the first time rings may have been found around a moon.
''Until now, only planets were known to have rings, but now Rhea seems to have some family ties to its ringed parent Saturn,'' Cassini scientist Geraint Jones said, who is also the lead author of the paper, Science Daily reported.
Rhea is roughly 1,500 kilometers in diameter. The apparent debris disk measures several thousand miles from end to end. The particles that make up the disk and any embedded rings probably range from the size of small pebbles to boulders.
An additional dust cloud may extend up to 5,900 kilometers from the moon's center, almost eight times the radius of Rhea.
''Like finding planets around other stars, and moons around asteroids, these findings are opening a new field of rings around moons,'' Norbert Krupp, a scientist with Cassini's Magnetospheric Imaging Instrument from the Max Planck Institute for Solar System Research said.
Since the discovery, Cassini scientists have carried out numerical simulations to determine if Rhea can maintain rings. The models show that Rhea's gravity field, in combination with its orbit around Saturn, could allow rings that form to remain in place for a very long time.
''Seeing almost the same signatures on either side of Rhea was the clincher,'' added Jones.
''After ruling out many other possibilities, we said these are most likely rings. No one was expecting rings around a moon,'' he added.
One possible explanation for these rings is that they are remnants from an asteroid or comet collision in Rhea's distant past. Such a collision may have pitched large quantities of gas and solid particles around Rhea.
Once the gas dissipated, all that remained were the ring particles. Other moons of Saturn, such as Mimas, show evidence of a catastrophic collision that almost tore the moon apart.
''The diversity in our solar system never fails to amaze us,'' co-author and Cassini scientist Candy Hansen said on the Ultraviolet Imaging Spectrograph at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
''Many years ago we thought Saturn was the only planet with rings. Now we may have a moon of Saturn that is a miniature version of its even more elaborately decorated parent,'' he added.
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