Whispers that the Milky Way is filled with planets have turned into a roar. Earlier this week, astronomers announced the discovery of 600 more exoplanet candidates, including one "super-Earth" which may be habitable.
The news strengthens many astronomers' suspicions that habitable planets are common and that more exciting discoveries are likely as better telescopes become available.
Called a super-Earth because it is only 3.6 times more massive than Earth and possibly rocky rather than gaseous, it resides in a 58-day orbit on the inner edge of its orange star's habitable zone. If protected by a thick, cloudy atmosphere, it could have liquid water on its surface. Called HD 85512b, the exoplanet is only the second small world to be found inside a habitable zone and lies just 36 light years away in the constellation of Vela. That is close enough for future telescopes to scour it for signs of life.
Planet-hunters announced their latest finds this week at the Extreme Solar Systems II conference in Moran, Wyoming. A ground-based telescope in Chile discovered 55 of these planets, including HD 85512b, using an instrument called the High Accuracy Radial Velocity Planets Searcher (HARPS). NASA's Kepler space telescope spotted the others, mostly much further away.
While the HARPS team monitors nearby stars for telltale wobbles caused by orbiting planets, Kepler scientists search a wide field of faraway stars, watching for planets that become silhouetted against their suns. The technique yields many candidates but confirmation is difficult over such great distances.
Still, the Kepler team reckons the vast majority of its finds are genuine, and of the newest batch roughly a quarter appear to be super-Earths. All this suggests that an Earth analogue will turn up sooner rather than later.