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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."
Not quite. It's very likely a good jump or powerful stride would send you flying off into space, as a moon of that size would likely have a very low gravity.
He who laughs last is stuck in a time dilation bubble.
Maybe because the discovery was in Boulder?
/ 20040816-pr-a.cfm
Cassini Imaging Central Laboratory for Operations
Space Science Institute, Boulder, Colo.
-- http://saturn.jpl.nasa.gov/news/press-releases-04
The line between the two is what they orbit. A moon orbits a planet, an asteroid orbits the Sun.
Of course, when whether we should just stop calling an object orbiting a planet a moon, and just call it a rock when it's past a certain minimum size, is up to the scientists.
Moons orbit other (non-solar) bodies. Ceres can't be a moon because it only orbits the Sun. Some asteroids have satellites (moons) themselves.
There is no set cut-off point, but several miles seems to be considered moon-sized, while the larger chunks in Saturn's rings aren't big enough at a few hundred feet.
A satellite is any object that orbits a planet, regardless of mass.
A moon is any natural object that orbits a planet, again regardless of mass. (so probes and debris don't qualify)
A planet is an object massive enough to become spherical under its own gravitationnal field, that orbits a star. An asteroid is any rocky object that orbits a star and doesn't qualify as a planet.
A moon doesn't have to be spherical, so that's why the two irregular moons of Mars, Phobos and Deimos (captured asteroids), are still called moons. The rings of saturn are made up of millions of small "moons", but they are (rightfully so) considered a single entity.
What about (-1, Obvious response to an obvious joke)
"I use a Mac because I'm just better than you are."
Is this guy onto something big, or is he delusional?
If you read more than a few paragraphs of Hoagland's work, it becomes pretty obvious that the latter is the case.
Hoagland is the one who is still obsessed with the "face on Mars," interprets JPEG image artifacts as proof of aliens, and so on.
"...always new atoms but always doing the same dance, remembering what the dance was yesterday." -Richard Feynman
There's a very interesting article at space.com entitled 'What is a Moon?'.
what keeps Io from becoming a ring?
Distance. Saturn's rings are within the Roche limit, Io is outside.
Some interesting thoughts about what exactly is a moon can be found here
From what i understand from the article is that nobody is sure what exactly the definition of a moon is.
For those too lazy to read the link, the result is a meteor with a diameter of about 7 km would be required to increase the escape velocity enough that you couldn't jump off. This of course assumes a certain density for the meteor and also that you are an olympic high-jumper. Also, it assumes that you can apply the same jumping force on the meteor as on the earth, which probably isn't true as you couldn't get a good running start. But it's an interesting result nonetheless, and using your definition these "moons" probably wouldn't qualify. Certainly comfortable walking would be impossible.
main(c,r){for(r=32;r;) printf(++c>31?c=!r--,"\n":c<r?" ":~c&r?" `":" #");}
Ask Phil Plait.
karma capped