Dark gaps separate the rings of Saturn in this 2009 image from the Cassini spacecraft. The gaps are cleared by the gravitational influence of small moons. (One of those moons, Epimetheus, casts a long shadow across the rings — the dark vertical streak at bottom center.) [NASA/JPL/SSI]
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Moon and Planets
The weekend wraps up with a beautiful display in the evening sky tonight: a tight grouping of the Moon and the bright planets Mars and Saturn. Yellow-orange Mars is close to the lower left of the Moon at nightfall, with golden Saturn about the same distance to the lower right of the Moon.
If you look at Mars through a telescope, you may spot the planet’s white polar ice caps, plus some large patches of bright orange — regions that are covered with dust — and other patches of dark gray — bare volcanic rock.
The main feature you’d see at Saturn, though, is its broad rings — wide bands of ice, rock, and dust that shine as brightly as the planet itself. The inner edge of the rings is about 7500 miles above Saturn’s bright cloudtops, while the outer edge of the main rings is about 85,000 miles out.
There are several dark gaps in the rings. They’re cleared out by the gravity of small moons that orbit inside the rings. They’re not completely clear, though, so you probably wouldn’t want to try flying through them.
A couple of smaller rings encircle the main rings. One of them is braided like a loaf of challah bread. It’s twisted by the gravity of the moon Enceladus. Enceladus also feeds that ring. Geysers of water and ice shoot into space from the moon’s south pole. Some of that material feeds into the ring, keeping it young and fresh.
Again, look for Saturn and Mars near the Moon this evening — a pretty way to end the weekend.
Script by Damond Benningfield, Copyright 2014