Kepler Planet-Detection Mission: Introduction and First Results

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Science  07 Jan 2010:
DOI: 10.1126/science.1185402


The Kepler Mission was designed to determine the frequency of Earth-size planets in and near the habitable zone of Sun-like stars. The habitable zone is that region where planetary temperatures are suitable for water to exist on the surface. During the first six weeks of observations, 156,000 stars were monitored and five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and orbital periods from 3.2 to 4.9 days were discovered. The density of the Neptune-size Kepler-4b is similar to Neptune and GJ 436b, even though the irradiation level is 800,000 times higher. Kepler-7b is one of the lowest density planets (~0.17 gr/cc) yet detected. Kepler-5b, 6b, and 8b confirm the existence of planets with densities lower than those predicted for gas giant planets.