Two New Saturnian Moons

Mixel writes "NASA's Cassini spacecraft, which has been orbiting saturn since the 30th of June has uncovered two previously unknown bodies. 'The moons are approximately 3 kilometers (2 miles) and 4 kilometers (2.5 miles) across -- smaller than the city of Boulder, Colorado.' The Huygens probe will be deployed to the large (bigger than Mercury!) yet mysterious moon, Titan, in December."

Comments

Millions of Moons

[Tablizer]

Saturn actually has millions of moons if you count the boulders in the rings. If you don't count them, then where is the cut-off point? This debate has never been settled, and may require an arbitrary cut-off size to get a clean definition.

Re:Millions of Moons

[Tablizer]

there's a problem at the other end of the scale too: our moon, the Moon, is so big that the Earth-Moon system could/should be considered a double-planet system.

I have heard a pretty good definition with the average center of orbit between the two bodies being inside the body of one of the pair. Our moon barely cuts it as a moon under this definition, but does, IIRC. However, such a definition does not work well with gasious planets since their boundary is fuzzy. But, it works pretty good with rocky bodies, at least fairly round ones.

Are they really moons?

[Anti Frozt]

Where do we draw the line between classifying a stellar body as a moon or an asteroid? Do we simply base it on the fact that it's a piece of rock orbiting a planet or is there some other defining characteristic?

Ceres, the largest asteroid in our solar system, has a diameter ~950 Km in length, much larger than many of the so-called moons we've discovered.