Astronomers have been looking for ET for almost half a century. So far, they haven't found him. But a team of astronomers has come up with a new approach that it says will greatly increase the chance of success: Look for civilizations that know we're here, and that are deliberately beaming signals our way.
The searches conducted so far have tried to pick up any signal that might come from an advanced civilization. That can include "stray" signals, like those from high-powered radars. The idea is that you just don't know who might be out there or where.
But Richard Henry, Seth Shostak, and others propose a new approach: Look for star systems that lie along the Sun's path across the sky, known as the ecliptic.
The reason is simple. As seen from those star systems, Earth periodically passes across the face of the Sun -- an event known as a transit. As seen from the distant star, that causes the Sun's light to dim a little. In fact, NASA's going to launch a spacecraft next year to hunt for transits in other star systems. Called Kepler, it'll search tens of thousands of stars, and could find evidence of hundreds of Earth-like planets.
What's more, as Earth passed across the Sun, an advanced civilization could use the transits to detect oxygen and other elements in our atmosphere -- indications that there's life here. And if they know there's life, they're more likely to beam a greeting in our direction. To find it, all we have to do is look.
Script by Damond Benningfield, Copyright 2008
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