When an exoplanet comes between its star and Charbonneau’s telescopes, it creates an interstellar eclipse that reveals the planet’s potential for life. Based on the amount of light that is blocked by the eclipse and the properties of the incoming light, researchers can calculate the planet’s density and atmospheric composition to check whether it’s habitable. And if the planet is in the so-called “Goldilocks Zone,” the range of orbital distances within which a planet is not too hot or cold, there may just be life.

Charbonneau’s approach is gaining wide-spread support. The Kepler Mission is a NASA-based program with the goal of finding Earth-like exoplanets. The Kepler space observatory was launched in the spring of 2009 and is expected to have results by late 2012. Charbonneau, who is also a member of the Kepler team, is confident that Kepler’s results will be positive. “If they’re out there, Kepler’s going to find them,” he says.

Charbonneau recognizes that his goals are not as ambitious as those of SETI—a confirmed extra-terrestrial radio signal. “They’re sort of in this one quadrant of very high risk, very high return science,” he says.

But he believes that, ultimately, the differing methods are two sides of the same coin.

“SETI and [the exoplanet] approach are very similar in terms of what they want to do, but they’re totally different in terms of underlying assumptions,” he says. “SETI requires intelligent life interested in communicating and interested in radio telescopes. The path we’re advocating is basically that there are inevitable things that life does to the atmosphere.”

He continues, “There was no intent to change the atmosphere on the part of photosynthetic bacteria billions of years ago; it’s just an inevitable consequence of their daily activities.”