Saturn’s UFO Moon Pic Just in Time For April Fools' Day. But It’s Real.

The entire universe in blog form
April 1 2013 1:10 PM

Cassini Spies a Forbidden Planet’s Flying Saucer Moon

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:

Cassini pic of Prometheus
Prometheus (the moon, not the movie) seen by the Cassini Saturn spaceprobe. Click to bringeroffirenate.

Image credit: NASA/JPL-Caltech/Space Science Institute

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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.

Prometheus
Prometheus up close and personal, from a Jan. 27, 2010 encounter by Cassini.

Image credit: NASA/JPL/Space Science Institute

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.

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!