Kepler I 
Summer may be starting to wind down, but the season's signature star pattern remains in great view. The Summer Triangle is high in the east at nightfall. Its brightest star, Vega, is highest in the sky then, with Deneb well to its lower left and Altair farther to its lower right.
A spacecraft called Kepler has been keeping an eye on a large chunk of sky between Vega and Deneb. It's watching more than 150,000 stars for evidence of planets. Its goal is to find Earth-size planets in Earth-like orbits around Sun-like stars.
Kepler looks for a star to get a bit fainter -- the result of a planet passing in front of the star as seen from Earth, dimming its light by a tiny bit. The astronomers who study Kepler's results want to see three of these events, known as transits, to confirm that they're seeing a planet.
COCHRAN: There are a number of other astrophysical phenomena that can mimic that type of a signal.
Texas astronomer Bill Cochran is a member of the Kepler team. He's using telescopes at McDonald Observatory to help confirm Kepler's discoveries.
COCHRAN: For instance, if there are two stars that are orbiting each other, and instead of one passing directly in front of the other it's just a grazing eclipse that they would show, then that might give a signal comparable to the size that we would see with a planet passing directly in front of the star. And we can actually separate out those various effects using ground-based telescopes.
More about that tomorrow.
Script by Damond Benningfield, Copyright 2011