Cassini Spies a Forbidden Planet’s Flying Saucer Moon

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Apr 1, 2013
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The Cassini spacecraft orbiting Saturn has taken a picture of a flying-saucer-shaped object using a force field to manipulate one of the planet’s rings.

Yes, I know what today is! But I assure you, this picture is quite real:

The object is Saturn’s moon Prometheus, a chunk of ice about 136 kilometers (85 miles) long. It orbits Saturn near the planet’s narrow F ring, and that’s no coincidence. Prometheus and its sister moon Pandora flank the ring (Prometheus on the inside—toward Saturn—and Pandora on the outer side), and the force of their gravity helps constrain the tight path of the ring particles. For this reason they’re called shepherd moons.

This picture threw me for a moment. Prometheus is elongated and potato-shaped, while Pandora is somewhat squatter. In some pictures Pandora is the one that looks like a flying saucer, but the angle of the sunlight here gives Prometheus a decidedly alien spaceshipy look. It looks very much like an April Fools' Day picture just posted by International Space Station Commander Chris Hadfield, too.

In fact, this looks so much like the United Planets Cruiser C57-D—on today of all days— I had to make sure this picture was real. As far as I can tell, it is. That’s good! After all, I wouldn’t want to create a Tempest in a teapot.