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Kepler-22b System Diagram.jpg
A diagram of the Kepler-22b System, compared to our Inner Solar System.
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus[1]
Right ascension 19h 16m 52.2s
Declination +47° 53′ 4.2″
Apparent magnitude (V) 11.664[2]
Spectral type G5[3]
Parallax (π) ~5.26 mas
Distance 620[3] ly
(190 pc)
Absolute magnitude (MV) ~5.27
Absolute bolometric
Mass 0.970 ± 0.060[2] M
Radius 0.979 ± 0.020[2] R
Luminosity (bolometric) 0.8 L
Luminosity (visual, LV) ~0.67 L
Temperature 5518 ± 44[2] K
Metallicity [Fe/H] –0.29 ± 0.06[2] dex
Rotational velocity (v sin i) 0.6 ± 1.0[2] km/s
Other designations
KOI-087,[4] KIC 10593626, 2MASS J19165219+4753040[5]
Database references
KIC data

Kepler-22 is a star in the northern constellation of Cygnus, the swan, that is orbited by a planet found to be unequivocally within the star's habitable zone. It is located at the celestial coordinates: Right Ascension 19h 16m 52.2s, Declination +47° 53′ 4.2″.[4] With an apparent visual magnitude of 11.7,[2] this star is too faint to be seen with the naked eye. It can be viewed with a telescope having an aperture of at least 4 in (10 cm).[6] The estimated distance to Kepler-22 is 620 light-years (190 parsecs).[3]

Kepler-22 is slightly smaller and cooler than the Sun,[7] with a lower abundance of elements having more mass than helium.[2] It has a spectral type of G5, while the luminosity class remains undetermined.[3] This star is radiating 79%[2] of the Sun's luminosity from its outer atmosphere at an effective temperature of 5,518 K,[2] giving it the yellow-hued glow of a G-type star.[8] A projected rotational velocity of 0.6 km/s[2] suggests it has a low period of rotation.

Planetary system[edit]

On December 5, 2011, scientists from the Kepler mission announced that a possible Earthlike world (Kepler-22b) had been discovered orbiting in the star's habitable zone by NASA's Kepler spacecraft.[9] This was significant in that it was the first relatively Earth-sized extrasolar planet (about twice as big)[10] confirmed to be orbiting within a star's habitable zone.[11]

The Kepler-22 planetary system[3]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b < 0.11 MJ 0.849 ± 0.018 289.8623 +0.016
2.4 R


  1. ^ "Cygnus – constellation boundary", The Constellations, International Astronomical Union, retrieved 2011-12-15 
  2. ^ a b c d e f g h i j k Kepler-22b, NASA Ames Research Center, retrieved 2011-12-06 
  3. ^ a b c d e Schneider, Jean, "Star: Kepler-22", Extrasolar Planets Encyclopaedia, Paris Observatory, retrieved 2011-12-06 
  4. ^ a b "Kepler Discoveries". 2011-12-05. 
  5. ^ "GSC 03546-02301 -- Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2011-12-08 
  6. ^ Sherrod, P. Clay; Koed, Thomas L. (2003), A Complete Manual of Amateur Astronomy: Tools and Techniques for Astronomical Observations, Astronomy Series, Courier Dover Publications, p. 9, ISBN 0486428206 
  7. ^ "Kepler Confirms First Planet in Habitable Zone of Sun-Like Star". Universe Today. 2011-12-05. 
  8. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16 
  9. ^ Boyle, Rebecca (December 5, 2011). "Kepler Team Confirms First Earth-like planet in a habitable zone, And Finds 1,094 More Worlds". Popular Science. Retrieved December 5, 2011. 
  10. ^ Singhal, Nishant Kumar. "DIGG Kepler Team Confirms First Earth-like Planet in a Habitable Zone, And Finds 1,094 More Worlds". Popular Science. Retrieved 15 December 2011. 
  11. ^ "NASA Telescope Confirms Alien Planet in Habitable Zone". 2011-12-05. 

Coordinates: Sky map 19h 16m 52.2s, +47° 53′ 4.2″