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Unmanned Spaceflight.com _ Cassini's ongoing mission and raw images _ Mimas And...?

Posted by: Palomar Sep 14 2005, 01:48 PM

http://www.saturntoday.com/news/viewsr.html?pid=18061

Unless my eyesight needs a checkup, there's another moon there. And a portion (band) of Rings. Those double-moon images are so cool.

Can anyone ID the other moon? I've looked elsewhere on the 'net for the same pic with additional info...no results yet.

Posted by: SigurRosFan Sep 14 2005, 02:06 PM

... Tethys(?).

At ~14:30 UTC / September 9.

Posted by: Rob Pinnegar Sep 14 2005, 02:18 PM

Well, it looks to be about four times bigger than Mimas, which makes one suspect it's probably Rhea. We need to remember that it won't be at the same distance from Cassini as Mimas, though, which will affect its apparent size. The range of this photo is two million kilometres. That's not quite enough to make the distance effect totally insignificant.

I don't think it could be Tethys, but Dione _might_ be able to look that much bigger than Mimas from that distance, if the orbital angles were right. Still, I'm betting on Rhea. In addition to the size factor, you can also see a bright ray crater on the larger moon. Rhea has one that looks a lot like that (Dione may also have one or two, but I'm punting here).

Posted by: Jyril Sep 14 2005, 03:19 PM

http://volcanopele.blogspot.com/2005/09/raw-images-of-day_12.html

Posted by: SigurRosFan Sep 14 2005, 03:33 PM

Yes. It's Rhea.

About 21:40 UTC / September 09.

http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=601&vbody=-82&month=9&day=9&year=2005&hour=21&minute=40&fovmul=1&rfov=1&bfov=30

Posted by: Palomar Sep 14 2005, 03:36 PM

*Thank you to everyone.