Catalog of Exoplanets

Did you know there are now over 300 confirmed planets orbiting suns other than our own?

That's the number as I write this, but the tally goes up on a regular basis. Also, the detection-level goes down, and we're close to the ability to detect earth-sized planets. The first planets discovered were huge, hot gasballs (insert your favorite Rush Limbaugh joke here). Those worlds are incapable of supporting life as we know it. But more recently, large rocky planets have been identified, so we're getting closer to being able to "see" other potential earths.

The trick will be to find a more or less Earth-sized rocky planet in the so-called "Goldilocks Zone" (really!). It sounds like a joke, but that's the casual name scientists use for the very real "sphere of habitability" around a star where an orbiting planet would be not too hot, not too cold, but just right for Earth-style life. (See? Scientists can have a sense of humor!)

The Planetary Society put up a web page that keeps a running tally of all known planets:
http://www.planetary.org/exoplanets/list.php. The list represents a ton of work collating the raw data and lets you click your way to learn more about everything there.

It's fun to be an armchair interstellar explorer, and especially fun to check the site every now and again to watch the totals grow.

It seems to be turning out that planets are actually quite common. It may even be unusual for a star NOT to have planets.

And someday soon, in the next few years, someone will announce the discovery of the first truly earthlike world in its star's sphere of habitability--- in the Goldilocks Zone. And then, with some real data instead of just educated guesses, we'll be able to pin down some of the hardest variables in the famous Drake Equation, and come up with a more refined estimate for whether there's life out there, or not.

But as of now, with every new discovery, the odds get better and better.

http://en.wikipedia.org/wiki/Drake_equation

Sagan's video on the Drake Equation (his estimate of the number of planets is probably way low, due to newer data that wasn't available to him when the video was made):
http://www.youtube.com/watch?v=0Ztl8CG3Sys