Kepler Orrery of exoplanets
All the multiple-planet systems discovered by Kepler, an exoplanet space mission of NASA, as of 2nd Feb. 2011; orbits go through the entire mission (3.5 years). Hot colors to Cool colors (Red to yellow to green to cyan to blue to gray) are Big planets to Smaller planets, relative to the other planets in the system.
Limits of planet hunting
This is in response to the blog post “Are we looking for aliens in the wrong places?”: Extrasolar planet is still the best place to look for extraterrestrial life. And Kepler is the best space mission so far to look for planets and perhaps planets hosting extraterrestrial life. But one can see how far is the reach of the whole mission compared to the size of the galaxy. We are not looking at the wrong place, but we constrained by what we can manage to see with various indirect methods of planet detection. And this is the place, where we can hope for some intelligent life to exist.