Kepler-22b: The First Confirmed Extrasolar Planet
Kepler-22b is the first confirmed extrasolar planet found by NASA's Kepler Space Telescope to orbit within the habitable zone of a Sun-like star. Kepler-22b, a possible super-Earth, is 600 light years away from Earth, in orbit around Kepler-22, a G-type star.The discovery was announced December 5, 2011. The planet was originally discovered on Kepler's third day of science operations in mid-2009.The third transit was detected in late 2010. Additional confirmation data was provided by the Spitzer Space Telescope and ground-based observations.Kepler-22b's radius is roughly 2.4 times the radius of Earth, or about 60% that of Neptune. Its mass and surface composition remain unknown,[7][6] with only some very rough estimates established: It has less than 124 Earth masses at the 3 sigma confidence limit, and less than 36 Earth masses at 1 sigma confidence.[8]
It has been estimated that it is probably a "Neptunian" (i.e. mass similar to Neptune[9]) planet with a mass of ~35 Earth masses[citation needed]. There are the possibilities that it could be an "ocean-like" world with only some 10 Earth masses.[10] It might also be comparable to GJ 1214 b in terms of radius, but Kepler-22b is, unlike that planet, in the habitable zone. If it has an Earth-like density (5.515 g/cm3) then it would contain 13.8 Earth masses,[note 1] while its surface gravity would be 2.4 times Earth's.[note 2]
Since Kepler-22b is substantially larger than our planet, it is likely to have a different composition than Earth, and depending on its actual mass, the planet could be rocky, liquid, or gaseous.[7].
If it is mostly ocean with a small rocky core, Natalie Batalha, one of the scientists on the project, speculated "it's not beyond the realm of possibility that life could exist in such an ocean."[11] This possibility of life has spurred SETI to perform research on top candidates for extraterrestrial intelligence.[12] However, if the planet's carbon cycle has ceased due to lack of oceans and
It has been estimated that it is probably a "Neptunian" (i.e. mass similar to Neptune[9]) planet with a mass of ~35 Earth masses[citation needed]. There are the possibilities that it could be an "ocean-like" world with only some 10 Earth masses.[10] It might also be comparable to GJ 1214 b in terms of radius, but Kepler-22b is, unlike that planet, in the habitable zone. If it has an Earth-like density (5.515 g/cm3) then it would contain 13.8 Earth masses,[note 1] while its surface gravity would be 2.4 times Earth's.[note 2]
Since Kepler-22b is substantially larger than our planet, it is likely to have a different composition than Earth, and depending on its actual mass, the planet could be rocky, liquid, or gaseous.[7].
If it is mostly ocean with a small rocky core, Natalie Batalha, one of the scientists on the project, speculated "it's not beyond the realm of possibility that life could exist in such an ocean."[11] This possibility of life has spurred SETI to perform research on top candidates for extraterrestrial intelligence.[12] However, if the planet's carbon cycle has ceased due to lack of oceans and