This artist’s rendition provided by NASA shows the Kepler space telescope, which is designed to search for Earth-like planets in the Milky Way galaxy.

Cape Canaveral, Fla. ? NASA will soon be on the lookout for possible Earths in one faraway corner of the galaxy.

A planet-hunting spacecraft, named Kepler after the German 17th-century astrophysicist, is scheduled to rocket away from Cape Canaveral tonight. Excellent launch weather is expected.

The telescope will spend 3 1/2 years staring at roughly 100,000 stars, measuring their brightness and any winks in the light that might signify orbiting planets.

“We certainly won’t find E.T., but we might find E.T.’s home by looking at all of these stars,” Bill Boruki, Kepler’s principal scientist, said Thursday.

Ed Weiler, NASA’s associate administrator for science, said Kepler is not just another science mission.

“It very possibly could tell us that Earths are very, very common, that we have lots of neighbors out there, or it could tell us that Earths are really, really, really rare,” Weiler said.

“Perhaps we’re the only Earth. I think that would be a very bad answer because I, for one, don’t want to live in an empty universe where we’re the best there is. That’s a scary thought to many of us.”

Kepler will be scouting for Earth-size planets circling stars in the so-called habitable or Goldilocks zone. That’s where planets are neither too close nor too far from their star, and where conditions could be ripe for liquid water on the surface.

The stars to be observed by Kepler are between 600 and 3,000 light years away.

Kepler is 15 feet high and 9 feet in diameter. The mission costs $600 million, from start to finish.