Thursday, February 28, 2008

Mini moons

Interlopers. Hangers-on. Hitch-hikers. Parasites. Guardian angels. Extended family. Entangled relationships from which you will never escape.

Take your pick.

The earth has more than one moon.

Okay, technically they aren't moons, since they don't rotate the earth, but are instead "co-orbital objects," that gravitationally interact with us as we make our way around the sun. They don't shine, they're too small to reflect back much sunlight, they are dark chunks of rock, leftover from the birth of the solar system.

And there are several of them, but I wanna talk about the largest one today.

3753 Cruithne (pronounced "krooy-nyuh," named for a King of the Celtic Picts) is the coolest of all, because of its very strange horseshoe shaped orbit. Of course, all orbits are ellipses, but from the point of view of the earth, Cruithne's orbit is a set of spirals that, taken together, form a horseshoe (the picture below is a simplified version). I'd be lying to say I understand it fully, and I've been pondering it for weeks now, but the result is a stable and carefully choreographed two-body orbit where neither object will hit the other one.

Please don't this this as a sign of intelligent design, or some uber-mind in charge of a great celestial clockworks. It's not. The reason Cruithne is in such a stable (albeit intricately choreographed) orbit is simply because if it were in an unstable orbit, it would have been flung into space, the sun, or even the earth. Like that thing that killed the dinosaurs. It's the cosmic version of "last man standing," and if it is evidence of anything, it is evidence of endless possibility, of the bounty of patterns nature can form from such simple building blocks.


Maggie said...

Have you read The God Delusion? I think you would enjoy it. It was excellent reading.

Eric Shonkwiler said...

You say not proof of intelligent design, I say proof of Satan, the Deceiver. Tomayto, tomato.

Nancy Dancehall said...

God put that in orbit just to test YOUR faith. Repent, sinner.


I don't know. My jury's out at the moment. I've got a blog tale for you regarding religion. I keep tripping over it lately.

Clowncar said...

Now, now, I didn't say there wasn't a God, just that Cruithne's orbit isn't proof of it.

Nor did I say there was a God.

Do tell, Nance.

Jo said...

I understand the spiral, why there's no collision...but I don't understand the horseshoe...what does Cruithne do during the gap? In any case, fascinating.

Jo said...

Next time lazy-me will click the link before I babble :P So Cruithne just turns around! Every time the stalking rock gets the courage to approach, Earth peppersprays it...then Cruithne spends a lot of time writing sad poetry until the situation repeats on the flip side :)

Mother of Invention said...

Man, you could do a lovely take on Poetry Word "DANCE" with all this "choreographed" movement you know so much about!

Clowncar said...

Asteroid as stalker. Hiding in the LaGrange Point of abandonment. Nice, Jo. Or scary, I guess; I've never been stalked.

MOI, I was tempted to use my Thursday post as my Friday Word O' The Day post, but it just seemed so lazy. My Midwestern work ethic wouldn't allow me.