Wednesday, October 21

Prognostications

I've never claimed to be the "prognosticator of prognosticators" or anything, but I did have a dream last night that the moon blew up. So, you should all be on the lookout.

2 comments:

Ben said...

I'm not sure what the tangible fallout from the moon blowing up would be. But aren't we well served by having it behind the earth right now so it won't block the sun? Or is my astro-geography wrong? I never had much of a sense for such things.

Clark said...

I'm not sure what you mean by the moon being "behind the earth right now." The moons orbital period is about 28 days, and we just had a new moon on Sunday. So, the moon is roughly between the earth and the sun right now. The moons orbit is inclined about 5° from the earths orbit, so it doesn't generally lie directly between us. But it does at least 2 (and up to 5) times per year, giving us solar eclipses. (Zero to 2 of these eclipses will be complete.)

Now, not having a moon would effect our orbit slightly, alter the length of our day, and remove the tides which might mess up our weather pretty badly. But, I think the bigger issue is that if the moon blew up, it is likely that a sizeable chunk of it would come crashing to earth. The Alvarez hypothesis is the theory that a big asteroid hit near Mexico and wiped out the dinosaurs about 65 million years ago. That chunk of rock would have been about 10km in diameter. The moon is about 3500km in diameter, making it about 42,000,000 more voluminous. I'm not sure what densities we'd be talking about here, but I think it's safe to say that the moon (density 3.3) is at least 10,000,000 times as dense as something that could cause large scale global extinction. Only a tiny, tiny bit of the moon would need to hit us to cause that.

Now, should a large portion strike the earth (~50%), it would probably kill all life on earth, and probably the the planet back a few billion years in its development.

Basically, the moon blowing up would be really bad.