Thursday, September 30, 2010

Another world

Ever since the first exoplanet was discovered in 1992, astronomers have been waiting for imaging techniques to advance enough to detect earth-size bodies close in in the habitable zone of stars. Now, they've found one:

Gliese 581g is the first world discovered beyond Earth that's the right size and location for life.


The discovery caps an 11-year effort to tease out information from instruments on ground-based telescopes that measure minute variations in starlight caused by the gravitational tugs of orbiting planets.

Planet G -- the sixth member in Gliese 581's family -- orbits right in the middle of that system's habitable region, where temperatures would be suitable for liquid water to pool on the planet's surface.

Which means we now have a possible answer to one of the variables in the Drake Equation - the likelihood that a life-zone planet will in fact develop life. Unfortunately, its 20 light years away - which absent Einstein being wrong, means it is completely physically inaccessible. We can look at it, and if we get a really, really big orbiting telescope, we can study it remotely and detect whether it has water and clouds. We might even, if we want to burn a substantial fraction of our gloabl energy output and wait a lifetime, send a tiny probe to take a closer look. But we can never go there. And we certainly can't go there to set up the new frontier beloved of science fiction and Libertarian space cadets.

The news of habitable extrasolar planets is fascinating, and it will tell us interesting things about the universe (not least: where the hell is everybody else?). But the cold reality of relativistic physics means we are pretty much stuck here. For practical purposes, the Earth and the rest of the solar system are all we've got, and all we'll ever have. So we'd better take care of them, because we have nowhere else to go.

[Hat-tip: Kiwipolitico]