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Cassini finds Saturn`s moons reshaping its rings

Last Updated: Thursday, October 15, 2009 - 16:03

Washington: Some deformations from the normal pattern in the shape of F ring, one of the seven rings of Saturn, have been recently captured by NASA`s Cassini spacecraft.

Scientists at NASA believe that the deformation in the shape of the ring, considered to be held together by its "shepherd moons" -- Prometheus and Pandora -- could be a result of the gravitational force exerted by the oblong moon Prometheus, visible just inside the ring.
The images captured by the spacecraft features channels carved into the ring supposedly when Prometheus occasionally forays into the ring structure while travelling on its
elliptical orbit.

"These so-called streamers are formed when the elliptical orbit of Prometheus brings the moon into the F ring. The gravity of the moon pulls material out of the ring,
carving out a new streamer on each 15-hour orbit," according to NASA.

A subtle deformation in the narrow F ring, situated approximately 1,40,180 kms from the centre of the planet, is also visible, in the images, toward the outer portion of the A
ring, which lies close to the F-ring.
The A ring is nearly 15,000 kilometers across while the F ring is just a few hundred kilometers broad at its widest point.

The planet`s seven rings are named A to G in the order they were discovered. From the innermost ring to the outermost the designators are D, C, B, A, F, G and E, according to the information on the website of "The Planetary Society", a space-interest group.

The spacecraft took the images in August this year, when it was on a mission to observe latest Saturn`s equinox, which takes place every 15 Earth years or so.

At the equinox, the plane of Saturn`s rings aligns with the Sun, casting shadows that bring out subtle details in their structure.

Shepherd moons are natural satellites that orbit near the outer edges of planetary rings or within gaps in the rings. They constrain the extent of the ring through their
gravitational influence.

Bureau Report

First Published: Thursday, October 15, 2009 - 16:03

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