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Moon and Saturn

September 27, 2014

Saturn is encircled by beautiful rings and more than 60 known moons. And there may be a link between the two — an idea supported by what appears to be a small moon taking shape inside the rings.

The possible moon is less than a mile across — too small to see directly. Last year, though, images from the Cassini spacecraft revealed a bright arc at the outer edge of Saturn’s A ring, the outermost of the planet’s main rings. The arc was hundreds of miles long, and may have formed when something hit the small moon and kicked off debris from its surface.

Planetary scientists think this part of the A ring is ripe for forming new moons. That’s because a larger moon, Janus, orbits beyond the A ring’s outer edge. The gravitational pull of Janus causes ring particles to crowd together. Some of these particles may merge, forming an ever-growing ball. Eventually, the ball may get big enough to form a moon.

Scientists don’t know when the new moon formed. It could have been during the past decade, or it could have been millions of years ago. Scientists hope to use Cassini to verify the discovery. It’s scheduled to pass close to the rings in 2016, possibly allowing it to see the moon directly — confirming what may be Saturn’s newest moon.

And Saturn is quite close to our own Moon this evening. The giant planet looks like a bright golden star close to the upper left of the crescent Moon as night falls. They set about an hour later.

Script by Ken Croswell, Copyright 2014

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