Today is a big day in the history of space exploration. Tonight the Kepler spacecraft launches. It's mission is to discover exoplanets - planets outside the solar system.

Big deal right? We've already discovered about 330 exoplanets. What makes Kepler special?

Its special because, for the first time, this is a spacecraft that is capable of finding earth-sized rocky planets within the habitable zone around sun-like stars. It's sci-fi without the "fi." We can, for the first time, claim part of the Star Trek intro as a mission statement for a real project:

...Its five-year mission: to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no one has gone before.

It's too bad we're not actually traveling to these worlds. For now. At least we'll know where to go when we can.