The Sciences

A marvelous night for a (Saturn) moon dance

Bad AstronomyBy Phil PlaitFeb 10, 2010 1:00 PM

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We live on a wonderful planet with a beautiful Moon. But I sometimes think we got gypped. The view from Saturn can be sooooo much cooler:

That's the moon Enceladus passing in front of (what we science-types call "transiting") Rhea. Enceladus is about 500 km (300 miles) across and Rhea is 3 times bigger. Rhea was about 2.7 million km (1.7 million miles) from Cassini when these shots were taken, and Enceladus a bit closer at 2.3 million km (1.4 million miles). Of course, by a bit closer I mean the same distance our Moon is from the Earth, so there was plenty of room for this mutual event. Here's a zoom of the middle frame:

Awesome. Note that these images were taken about one minute apart, so things were hopping. It's amazing to me that not only can we put a probe around Saturn and get images of its moons, but our math and physics are so freaking accurate we can say, "Hey, you know what? On this date at this time if we turn Cassini that way we'll see a moon over 2 million kilometers away pass in front of another one nearly 3 million kilometers away." Every morning, I have a 50/50 chance of finding my keys. That kinda puts things in perspective.

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