Wednesday, September 01, 2004

Extra-Solar Planets

Keep track of them as the discoveries pile up on this excellent site. Newspapers get scary when they try to do science (in the latest round of discoveries, the Philadelphia Inquirer identified "mu Arae" as the name of the planet, not the star).

The reporting tends to get breathy as the size of the planets being found get closer and closer to the size of the Earth. But the other side of that is, they're being found in places where planets that big shouldn't be, according to what we think we know about how solar systems form. Massive gas giants circling their suns in orbits tighter than Mercury's? There are three possibilities:

1. Our method of measuring the orbits or sizes of these newfound planets is wrong. (Seems unlikely.)

2. Our understanding of how solar systems are formed is way off. Probably, and that's not entirely surprising. But the range of astrophysics involved here is pretty limited. You can't introduce Mickey Mouse in a wizard's cap to conjure up worlds where they don't belong.

3. The gas giants formed in the "right" places (where our models predict them), and then spiralled in to their current close orbits. This might be the most likely explanation, and it's also the most depressing, because it means any Earth-like planets that once orbited in between have been blown out or chased into the star itself. Depressing development if you're looking for life in space or future homes for homo sapiens.