Kepler space mission: Detection of Earth-size planets in the habitable zone of solar-like stars

Abstract

The first step in discovering the extent of life in our galaxy is to determine the number of terrestrial planets in a habitable zone (HZ) of solar-like stars. Recent discoveries based on the Doppler-velocity technique have shown that many stars have giant planets, but this technique cannot detect Earth-size planets orbiting solar-like stars. The Kepler Mission is based on observing transits and is designed specifically to determine the frequency of terrestrial planets in a HZ. It was launched and is now monitoring 150,000 solar-like stars to detect patterns of transits that provide the size of the planet relative to the star and its orbital period. Combining these measurements with ground-based spectroscopy fixes the stellar parameters, the planet radius, orbital distance, and location relative to the HZ. Hundreds of terrestrial planets should be discovered before the mission ends, implying that life might be ubiquitous in our galaxy. Five large planets have been discovered already.