Saturn's icy moon Enceladus (background) slides behind Dione in this series of images shot by the Cassini spacecraft on September 8. Saturn has an entourage of more than 50 known moons, some of which share orbits around the giant planet. Enceladus and Dione are among the larger moons, however, so they don't have to share their orbital paths with any others. [NASA/JPL/SSI]
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Moon and Saturn
It sounds like something out of mythology -- or maybe the name of a rock band. But Saturn's hexagon is neither -- it's a structure in the clouds at the giant planet's north pole. And scientists are still trying to explain it.
The twin Voyager spacecraft discovered the hexagon when they flew by Saturn in the early 1980s. The structure was still there when the Cassini spacecraft entered orbit around Saturn almost a quarter-century later -- and it's still going strong today.
The hexagon spans about 15,000 miles, centered on the north pole. Its six sides -- outlined by clouds that extend deep into Saturn's thick atmosphere -- are all about the same length, and they're all about equally straight.
Like most of Saturn, the north pole is buffeted by strong winds. A giant storm sits inside the hexagon, and spins at more than 300 miles an hour. And the clouds that form the hexagon move at about the same speed. But the hexagon itself stays in place -- it spins at the same rate as the planet.
The hexagon may be created by "standing waves" -- ripples in the atmosphere that reflect back on themselves. But so far, that idea hasn't been confirmed -- and there's no explanation for what drives the waves in the first place. So Saturn's hexagon remains a bit of a mystery.
Look for Saturn quite near the Moon late tonight. They rise around midnight, with Saturn to the left of the Moon. It looks like a fairly bright golden star.
Script by Damond Benningfield, Copyright 2009
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