Newfound moon may be source of Saturns G ring

March 4th, 2009 - 12:50 pm ICT by ANI  

Washington, March 4 (ANI): NASAs Cassini spacecraft has found within Saturns G ring an embedded moonlet that appears as a faint, moving pinprick of light, which scientists believe is the main source of the G ring and its single ring arc.

Cassini imaging scientists analyzing images acquired over the course of about 600 days found the tiny moonlet, half a kilometer (about a third of a mile) across, embedded within a partial ring, or ring arc, previously found by Cassini in Saturns tenuous G ring.

Before Cassini, the G ring was the only dusty ring that was not clearly associated with a known moon, which made it odd, said Matthew Hedman, a Cassini imaging team associate at Cornell University in Ithaca, N.Y.

The discovery of this moonlet, together with other Cassini data, should help us make sense of this previously mysterious ring, he added.

Saturns rings were named in the order they were discovered. Working outward they are: D, C, B, A, F, G and E. The G ring is one of the outer diffuse rings.

Within the faint G ring there is a relatively bright and narrow, 250-kilometer-wide (150-miles) arc of ring material, which extends 150,000 kilometers (90,000 miles), or one-sixth of the way around the rings circumference.

The moonlet moves within this ring arc.

Scientists imaged the moonlet on August 15, 2008, and then they confirmed its presence by finding it in two earlier images.

They have since seen the moonlet on multiple occasions, most recently on Feb. 20, 2009.

The moonlet is too small to be resolved by Cassinis cameras, so its size cannot be measured directly.

However, Cassini scientists estimated the moonlets size by comparing its brightness to another small Saturnian moon, Pallene.

Hedman and his collaborators also have found that the moonlets orbit is being disturbed by the larger, nearby moon Mimas, which is responsible for keeping the ring arc together.

This brings the number of Saturnian ring arcs with embedded moonlets found by Cassini to three. The new moonlet may not be alone in the G ring arc.

According to Carl Murray, a Cassini imaging team member and professor at Queen Mary, University of London, The moons discovery and the disturbance of its trajectory by the neighboring moon Mimas highlight the close association between moons and rings that we see throughout the Saturn system.

Hopefully, we will learn in the future more about how such arcs form and interact with their parent bodies, he added. (ANI)

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