Where's Saturn's moon Mimas? Only the shadow knows...

NASA/JPL/Space Science Institute
Mimas casts a long shadow across Saturn's rings. The British astronomer Sir William Herschel discovered Mimas in 1789. It's 198 kilometers across (about 123 miles) on average (it's actually somewhat egg-shaped). Mimas is the bulldozer responsible for clearing material out of Saturn's Cassini Gap, a wide swath of space between the planet's A and B rings.

NASA's Cassini orbiter has long been the robotic Ansel Adams of the Saturn system.

As Saturn approaches its equinox, the hardy obiter is sending back one image after another that provide stunning views of the rings, moons, and in this rare case, the hint of a moon's presence from its shadow.

Cassini took the shot with its wide-angle camera back in April. The team released the image today.

If you can spare a few minutes, check out CICLOPS. It's the Cassini team's imaging laboratory at the Space Science Institute in Boulder, Colo.  And it's massing an amazing photo album from the Cassini mission, now into its fifth year orbiting Saturn and its moons. The primary mission ended in 2008. It's now in a two-year extension dubbed, surprise, surprise, the Cassini Equinox mission.

You'll find a few extra images in the series above. Enjoy!

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