Tuesday, July 27, 2004

Multi-Mooned Menace

I've been thinking about moons. Maybe it has something to do with Cassini.

Anyway, I was looking up at our ridiculously huge moon and thinking about how, in fantasy and SF, every single freakin' planet has about six moons, purple and green and red, crowded together to make a nice picturesque backdrop and, by the way, make it absolutely clear that we are not on Earth. Ok, fine, you need some way to get that across. "This was not Earth. This was Kwaxaqikutuz. The huge triple moons spun balefully overhead, pouring reddish purple light over the landscape, which was not on Earth, no! It was Kwaxaqikutuz! Kwaxaqikutuz! The planet which hereinafter is referred to as Planet K!" You get the picture, I suppose, though probably you do not buy the book.

So, geek that I am, I think about moons and I wonder about how multiple moons have become visual shorthand for alien, especially given that a system with more than two objects of comparable mass is not stable. If I am not totally mistaken the tendency is for at least one of the objects to get thrown out of the group at some point. Only when there is a significantly larger central mass, and the satellites are far enough apart to keep from perturbing each other's orbits too much, do you get a stable system. But tiny moons like Phobos and Deimos are no fun at all.

On the other hand, maybe I'm imagining things. I couldn't find a good example of this kind of picture, and I googled for almost five whole minutes.

1 comment:

Anonymous said...

Well, an inappropriate number of moons is something that can only mean a different planet, unlike other kinds of landscape weirdness. And it's more "spacey".

It's probably a good thing that Earth type planets tend to have only one satellite. Too many moons and their chaotic orbits would make it very difficult for astronomers to fit their motion to a sensible cosmological model. On the other hand, no moons and no other planets in the solar system would be much more confusing. No retrograde motion to observe, no phases, no eclipses. How any scientist in those circumstances could be able to develop theories of gravitaion, or even a heliocentric model, is beyond me.

(hate the way blogger does comments)