In a special audio interview (below), Michael Banks catches up with astronomer Alan Boss from the Carnegie Institution in Washington to talk about the hunt for a second Earth. Indeed, Boss thinks that Kepler may have already spotted a planet in the 1235 candidates with a similar mass to Earth, which orbits at a distance from its star where life could flourish. “Kepler has a couple of candidates. But we have to wait three or four years to see enough transits to make it believable,” says Boss. “The enticing thing about Kepler is that we know it has the precision to find Earth-like planets.”

Kepler is also teaching us more about the myriad of stars in the universe and Boss says that the mission may even spot the first moon outside our solar system. “Finding a moon would be a bit difficult although one would hope that Kepler could do it”, says the 60-year-old astronomer. “As Kepler can see a lot of gas giant planets, if one of those has an Earth-sized moon to it then it could potentially be seen in the Kepler data.”

Not resting on his laurels, Boss is already planning for the next mission after Kepler to start examining our nearest Earth-like planet and calls for funding to start building such a probe. “Once Kepler shows us that Earth-sized planets are common then there will be more pressure from scientists and the public to say ‘why don’t we go out there and study those that are close’,” says Boss. “Scientists know how to do this and they just need the money.”

Boss is the author of two books – Looking for Earths: The Race to Find New Solar Systems and The Crowded Universe: The Search for Living Planets. He also wrote a feature on extrasolar planets for the March 2009 issue of Physics World, which marked the 2009 International Year of Astronomy.