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Moon and Saturn

March 29, 2013

The space around Saturn, the second-largest planet in the solar system, is pretty crowded. The planet has more than 60 known moons, plus a system of bright, beautiful rings that spans more than a half-million miles. Many of the moons orbit inside the rings, clearing paths around themselves and keeping the rings together.

Several sets of moons actually share orbital paths. Tethys, which is one of the planet’s larger moons, is flanked by Telesto and Calypso, which are much smaller chunks of rock. And another major moon, Dione, shares an orbit with Polydeuces and Helene.

The moons Prometheus and Pandora don’t quite share an orbit. But their paths are so close together that the gravitational pull of each moon slightly alters the orbit of the other every time they pass each other.

And another pair of moons, Janus and Epimetheus, shares two orbits. Each moon is about 50,000 miles above Saturn’s cloudtops, in orbits that are only a few dozen miles apart. But every four years or so, they dance a gravitational tango that ends with them switching orbits - one drops to a slightly lower, faster track, while the other jumps to a higher, slower path. That stirs up the particles of rock and ice in the surrounding rings - keeping things busy in the crowded Saturn system.

Look for Saturn rising directly above our own moon late this evening, and to the right of the Moon at first light tomorrow. Saturn looks like a bright golden star.


Script by Damond Benningfield, Copyright 2013

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