Earth has a third satellite?

September 11, 2002 9:59 AM

Earth has a third satellite? Somehow I missed that a second one, Cruithne, was discovered in 1986. Is there a size or distance limit to something being considered a satellite?
posted by onhazier (31 comments total)

More Cruithne. Scooped, damn you!
posted by interrobang at 10:02 AM on September 11, 2002

What does 3753 Cruithne stand for?
posted by Irontom at 10:08 AM on September 11, 2002

Actually, fifth. "(Sept 18 2001) There are now two more near-Earth asteroids known to be currently in resonant states similar to those of Cruithne. These are 1998 UP1 and 2000 PH5. We are currently in the process of preparing these results for publishing. Look for more information on these fascinating new asteroids soon. "
posted by SpecialK at 10:08 AM on September 11, 2002

Irontom, 3753 is the astroid number for Cruithne.
posted by onhazier at 10:09 AM on September 11, 2002

Has anyone identified anything out at the Lagrange points yet? Or is the Lagrange system totally theoretical?
posted by alumshubby at 10:14 AM on September 11, 2002

alumshubby -- see more at onhazier's second link re L-points.
posted by briank at 10:25 AM on September 11, 2002

Cruithne orbits the sun, not the earth. Its orbit is tied to that of the earth, but that doesn't make it a satellite of the earth.

alumshubby, there have been objects identified at Lagrange points. The most famous examples are the Trojan asteroids, which share Jupiter's orbit around the sun. See http://www.physics.montana.edu/faculty/cornish/lagrange.html
for more information.
posted by hari at 10:28 AM on September 11, 2002

Lagrange points are real, like hari notes, there are numerous objects located at the lagrange points for saturn, jupiter and uranus. If there are any objects at Earth's lagrange points, they would be incredibly small and weakly held because we are so small and low-mass in comparison to Jupiter.

This and other resonant asteroids aren't satellites. The term satellite implies a 'two body' relationship, where the motion of the two objects is determined only by their mutual gravitation and motion. The case of these resonant asteroids is a 'three body' relationship, because the motion of the asteroids is determined by the Earth AND the Sun.

However, even though it isn't a 'moon', its still interesting in that its orbit shares our own, yet keenly avoids hitting us as it loops about in its odd orbit of us.
posted by phidauex at 10:39 AM on September 11, 2002

how large an object(s) are we talking about? feet? miles?
posted by ParisParamus at 10:45 AM on September 11, 2002

This naming of these bodies has me worried. If enough of them are found will there be mounting pressure to name the moon? If this is possible then can we pass a rule now that will prohibit something like the "Home Depot Moon"
posted by mss at 10:46 AM on September 11, 2002 [1 favorite]

I, for one, welcome our newly-arrived third satelite overlords.
posted by jazon at 10:47 AM on September 11, 2002

I always was under the impression that the Moon did have a name: Luna.
posted by kokogiak at 10:51 AM on September 11, 2002

Story from space.com: Newfound Object Orbiting Earth is Likely Apollo Junk.
posted by Quinn at 11:09 AM on September 11, 2002

Is there a freshness date on the overlords joke? Can someone turn it upside down and look? Or do a sniff test?
posted by poseur at 11:37 AM on September 11, 2002

Cruithne is not technically a satellite. Its orbit is synchronized with the Earth, though. It has often been called Earth's "second moon". I had also thought about doing a post a while back on Cruithne and on the Sun's binary companion Nemesis .
posted by vacapinta at 11:37 AM on September 11, 2002

Yeah, poseur, it is stale, but that's all I could think of while reading the article - newly arrived, unknown, possibly natural but maybe artificial. It also made me think of Issac Asimov's FOUND
posted by jazon at 11:43 AM on September 11, 2002

However, even though it isn't a 'moon', its still interesting in that its orbit shares our own, yet keenly avoids hitting us as it loops about in its odd orbit of us.

Interesting? If it didn't avoid hitting us we wouldn't be talking about it. It's sort of an anthropic principle type thingy.
posted by badstone at 11:52 AM on September 11, 2002

That's no moon...
posted by inpHilltr8r at 12:14 PM on September 11, 2002

Has anyone identified anything out at the Lagrange points yet?

Well, rumors are spreadin' 'round 'bout the "objects" outside Lagrange. Just lemme know if ya wanna go....
posted by m@ at 12:27 PM on September 11, 2002

Paging m(a). Black helicopters are waiting in the lobby.
posted by soundofsuburbia at 12:32 PM on September 11, 2002

Um, onhazier, Irontom was quoting the faq, and also using a google-bomb link style that is found in certain blogs, e.g. Scripting News, which uses the "What is X?" construction when linking to an explanatory page on X all the time.

And the Moon has a name: it's "the Moon", with a capital M. Other satellites of this planet or others may also be moons, but they are not named the Moon. As you can see, with 3753 asteroids and counting, there hasn't been a lot of confusion just yet.
posted by dhartung at 12:38 PM on September 11, 2002

watching those animations makes me wanna go find my old Spirograph kit.
posted by GeekAnimator at 12:46 PM on September 11, 2002

Will any of these moons or asteroids ever hit us and put us all out of our misery, please?

Or at least just hit the mtv buildings and satellites, please?

Or even just that one guy responsible for all the boy bands of the last decade, please!
posted by kileregreen at 12:54 PM on September 11, 2002

Psst, soundofsuburbia, the answer is here but don't tell anyone.
posted by m@ at 1:33 PM on September 11, 2002

M(a): Hehe! I suppose I'm not as down with classic american rock'n'roll as I thoght I was.
posted by soundofsuburbia at 2:07 PM on September 11, 2002

Did that make sense? I've had a few beers.
posted by soundofsuburbia at 2:08 PM on September 11, 2002

Bill Yeung's account of the discovery [Google cache of Bill Yeung's web site]
posted by roboto at 4:04 PM on September 11, 2002

Hey, who's up for a road trip? I call shotgun!
posted by billsaysthis at 8:28 PM on September 11, 2002

On naming the moon.
posted by thijsk at 1:40 AM on September 12, 2002

Wow, going off against boy bands and MTV! What a saucy, devil-may-care attitude you display!
posted by anildash at 4:24 AM on September 12, 2002

Latest - its a piece of space junk, probably from Apollo 12. And apparently there's an outside chance it will hit the moon.
posted by edh at 7:37 AM on September 12, 2002