Cassini May Have Witnessed the Birth of a New Saturn Moon!

by Rachel Baker on April 16, 2014

Either one gives birth or one doesn’t…unless that ‘one’ is Saturn, then its perfectly reasonable to leave everyone guessing.

The potential moon (nicknamed Peggy) is tiny, probably only about a kilometer (0.6 miles) across—really a moonlet—and is invisible in the Cassini pictures. However, its presence is betrayed by an odd clumping of material at the very edge of Saturn’s A ring, the outermost of Saturn’s main rings.

It was discovered by accident in an image taken on April 15, 2013—one year ago today. The picture above shows the main rings, the thin F ring outside them, and the irregularly shaped moon Prometheus (the actual target of the shot) in the center just inside the F ring. If you look carefully you can see a blob on the edge of the A ring. Here’s a close-up, with the clump indicated:

That’s clearly not a discrete object; it’s about 10 kilometers (6 miles) wide and 1,200 kilometers (740 miles) long, but this is what you would expect if a small object were located near the edge of the ring—and why astronomers think there’s most likely a moonlet there. It would have feeble gravity, but enough to affect the ice particles in the ring, creating the long, trailing clump.

Read the whole article here:
http://www.slate.com/blogs/bad_astronomy/2014/04/15/saturn_cassini_may_have_photographed_the_birth_of_a_moon.html

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