The Kepler space telescope is designed to look for planets like Earth that could have life. But no one expected it to find 54 planet-candidates at Goldilocks distances from their stars – not too warm or cold for life as we know it – in its first four months of operation.
NASA's Kepler spacecraft has uncovered 54 planet-candidates that orbit within their host stars' "habitable zones" – Goldilocks distances where the star warms the planet sufficiently to allow liquid water to remain stable on its surface.
The potential finds, which must clear an arduous, detailed confirmation process, still fall short of the ultimate goal, finding an Earth-size planet orbiting a sun-like star at Earth-like distances.
But if these candidates pan out as planets, their discovery – and its implications for uncovering many more as time passes – increases the likelihood that life has gained footholds elsewhere in the galaxy.
Five of the 54 candidates are near Earth's size but orbit smaller, dimmer stars that the sun. Others range in size from twice Earth's radius to larger than Jupiter. If these turn out to be planets, researchers speculate that any moons they might have could be habitable, even if the planet itself isn't.
These 54 objects appear on an overall list of 1,235 planet-candidates Kepler has detected during its first four months of operation – a pace significantly faster than even it's biggest supporters expected.
Last March, accomplished planet-hunter Debra Fischer, a Yale astronomer who is not a member of the Kepler team, suggested that Kepler's first year of operation would be dominated by discoveries of star-hugging, Jupiter-class planets, because those would be the easiest to spot. Only after three years of operation would Kepler begin to uncover Earth-scale planets, she forecast.
Instead, Kepler has served up a list of potential planets that includes 68 Earth-sized objects, 288 "super Earths," 662 Neptune-class objects, 165 Jupiter-scale objects, and 19 objects larger than Jupiter.