NASA Ames Research Center, Moffett Field, CA 94035, USA.
Science. 2010 Feb 19;327(5968):977-80. doi: 10.1126/science.1185402. Epub 2010 Jan 7.
The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet's surface. During the first 6 weeks of observations, Kepler monitored 156,000 stars, 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-sized Kepler-4b is similar to that of Neptune and GJ 436b, even though the irradiation level is 800,000 times higher. Kepler-7b is one of the lowest-density planets (approximately 0.17 gram per cubic centimeter) yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets with densities lower than those predicted for gas giant planets.
开普勒任务旨在确定类似太阳的恒星的宜居带内和附近的地球大小的行星的频率。宜居带是行星表面的温度适合水存在的区域。在最初的 6 周观测中，开普勒监测了 156000 颗恒星，发现了五颗新的系外行星，它们的大小在 0.37 到 1.6 木星半径之间，轨道周期为 3.2 到 4.9 天。海王星大小的 Kepler-4b 的密度与海王星和 GJ 436b 相似，尽管辐照度高 80 万倍。Kepler-7b 是迄今为止探测到的密度最低的行星之一（约为每立方厘米 0.17 克）。开普勒-5b、-6b 和-8b 证实了存在密度低于预测的气态巨行星的行星。
