Title: Discovery and Validation of Kepler-452b: A 1.6-Re Super Earth Exoplanet in the Habitable Zone of a G2 Star Author: Jon M. Jenkins, Joseph D. Twicken, Natalie M. Batalha, Douglas A. Caldwell, William D. Cochran, Michael Endl, David W. Latham, Gilbert A. Esquerdo, Shawn Seader, Allyson Bieryla, Erik Petigura, David R. Ciardi, Geoffrey W. Marcy, Howard Isaacson, Daniel Huber, Jason F. Rowe, Guillermo Torres, Stephen T. Bryson, Lars Buchhave, Ivan Ramirez, Angie Wolfgang, Jie Li, Jennifer R. Campbell, Peter Tenenbaum, Dwight Sanderfer, Christopher E. Henze, Joseph H. Catanzarite, Ronald L. Gilliland, William J. Borucki
We report on the discovery and validation of Kepler-452b, a transiting planet identified by a search through the 4 years of data collected by NASA's Kepler Mission. This possibly rocky 1.63^{+0.23}_{-0.20} Earth radii planet orbits its G2 host star every 384.843^{+0.007}_{0.012} days, the longest orbital period for a small (R_p < 2 Earth radii) transiting exoplanet to date. The likelihood that this planet has a rocky composition lies between 49% and 62%. The star has an effective temperature of 5757±85 K and a log g of 4.32±0.09. At a mean orbital separation of 1.046^{+0.019}_{-0.015} AU, this small planet is well within the optimistic habitable zone of its star (recent Venus/early Mars), experiencing only 10% more flux than Earth receives from the Sun today, and slightly outside the conservative habitable zone (runaway greenhouse/maximum greenhouse). The star is slightly larger and older than the Sun, with a present radius of 1.11^{+0.15}_{-0.09} solar radii and an estimated age of 6 Gyr. Thus, Kepler-452b has likely always been in the habitable zone and should remain there for another 3 Gyr.
A haul of planets from Nasa's Kepler telescope includes a world sharing many characteristics with Earth. Kepler-452b orbits at a very similar distance from its star, though its radius is 60% larger. Nasa scientists said they believe it is the most Earth-like planet yet. Read more
The first exoplanet orbiting another star like our sun was discovered in 1995. Exoplanets, especially small Earth-size worlds, belonged within the realm of science fiction just 21 years ago. Today, and thousands of discoveries later, astronomers are on the cusp of finding something people have dreamed about for thousands of years -- another Earth. Read more
Kepler-452b is an exoplanet orbiting the G-class star Kepler-452, identified by the Kepler spacecraft. Its discovery was publicly announced by NASA on 23 July 2015, and it is the first near-Earth-size planet discovered orbiting within the habitable zone of a star very similar to the Sun. Read more