The Holy Grail of NASA’s Kepler mission is the identification of what have become popularly known as “Earth twins”: Earth-size planets in Earth-like orbits around Sun-like stars. Such worlds would be the closest analogs to Earth with much better prospects of being habitable given our limited knowledge at this time. While a number of potentially habitable planets have been identified among Kepler’s ever-increasing haul of confirmed exoplanetary finds, all of them have been found orbiting dim K and M-dwarf stars which present a number of still unresolved issues potentially affecting their habitability. All that changed a couple of weeks ago with NASA’s announcement of the discovery of Kepler 452b. While there is little doubt that this world orbits just inside of the habitable zone of a Sun-like star, is it really a rocky planet or another mini-Neptune with no likelihood of being habitable in the conventional sense?
My latest essay for Centauri Dreams, entitled “Is Kepler 452b a Rocky Planet or Not?”, I take a close look at the claim made by the discovery team that there is a greater than 50% chance that Kepler 452b (formerly known as KIC 8311864b and originally discussed in “The First Look at Kepler’s Complete Primary Mission Data Set“) is a rocky planet. With a radius of 1.6 times that of the Earth, this newly discovered world seems to be in the middle of the transition from rocky planet to mini-Neptune based on recent analyses of other Kepler finds. While Kepler 452b is a promising target for future scientific study no matter what kind of world it turns out to be, the picture might not be quite as rosy as was painted in NASA’s announcement.
“Is Kepler 452b a Rocky Planet or Not?”, Centauri Dreams, August 7, 2015 [Post]
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Related Reading
“Habitable Planet Reality Check: Kepler 452b”, Drew Ex Machina, July 24, 2015 [Post]
“First Look at Kepler’s Complete Primary Mission Data Set”, Drew Ex Machina, January 26, 2015 [Post]
“Habitable Planet Reality Check: Terrestrial Planet Size Limit”, Drew Ex Machina, July 24, 2014 [Post]
“A Mass-Radius Relationship for ‘Sub-Neptunes’”, Centauri Dreams, May 22, 2015 [Post]
“A Review of the Best Habitable Planet Candidates”, Centauri Dreams, January 30, 2015 [Post]