E.T. Hunters Shift Gears

June 6, 2008 -- Scientists scouring the skies for radio waves from any extraterrestrial neighbors had an epiphany recently: Assume ET knows about us and wants to make contact.

Under that framework, the best place to look for cosmic neighbors would be around stars that lie more or less along lines of sight of Earth, a region known as the ecliptic, or the plane of Earth's orbit.

From this vantage point, an extraterrestrial civilization would be able to detect Earth as it passes in front of the sun, much the same way scientists on Earth have found planets circling stars beyond our solar system.

The ecliptic encompasses about 3 percent of the sky.

"Our team hopes this is a concept that should lead rapidly to the detection of other civilizations -- if they exist," Johns Hopkins University astronomer Richard Henry told reporters at the American Astronomical Society meeting this week in St. Louis, Mo.

"It's conceptual breakthrough," Henry said. "If the hypothesis is correct, they know Earth exists, and they know there is life on Earth."

Advanced civilizations would have the tools to make a chemical analysis of Earth's atmosphere, Henry said, which would reveal our planet's atmosphere is rich with water and oxygen.

"The inescapable implication is that Earth has life," he said.