Kepler-1229b^[1] (also known by its Kepler Object of Interest designationKOI-2418.01) is a confirmedsuper-Earthexoplanet, likelyrocky, orbiting within thehabitable zone of thered dwarfKepler-1229, located about 870light years (267parsecs) from Earth in the constellation ofCygnus.^[4][2] It was discovered in 2016 by theKepler space telescope.^[5] The exoplanet was found by using thetransit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured.

Kepler-1229b is likely a rockysuper-Earth, an exoplanet with a radius and mass bigger than Earth, but smaller than that of the gas giantsNeptune andUranus. It is 2.7 times the mass of earth. It has anequilibrium temperature of 213 K (−60 °C; −76 °F).^[3]

The planet orbits a (M-type)star namedKepler-1229, orbited by a total of one planet. The star has a mass of 0.54M_☉ and a radius of 0.51R_☉. It has a temperature of 3724K and is about 3.72 billion years old.^[2] In comparison, theSun is 4.6 billion years old^[6] and has a temperature of 5778 K.^[7]

The star'sapparent magnitude, or how bright it appears from Earth's perspective, is 15.474. Therefore, it is too dim to be seen with the naked eye.

Kepler-1229b orbits its host star with about 4% of the Sun's luminosity every 86.829 days at a distance of0.2896 AU (close to that ofMercury, which orbits at a distance of 0.387 AU).

The exoplanet, along with eight others, was announced to be orbiting in the habitable zone of its parent star, the region where, with the correct conditions and atmospheric properties, liquid water may exist on the surface of the planet.^[5] Kepler-1229b has a radius of 1.4R_🜨, so it is likely rocky. Its host star is ared dwarf, with about half as much mass than the Sun does. As a result, stars like Kepler-1229 have the ability to live up to 50–60 billion years, 5–6 times longer than the Sun will live.^[8]

In 2013, before the two wheels failed,NASA'sKepler spacecraft was completing observing stars on itsphotometer, the instrument it uses to detecttransit events, in which a planet crosses in front of and dims its host star for a brief and near-regular period of time. In this last test, Kepler observed50000 stars in theKepler Input Catalog, including Kepler-1229; the preliminary light curves were sent to the Kepler science team for analysis, who chose obvious planetary companions from the bunch for follow-up at observatories. The radial velocity observations confirmed that a planetary body was responsible for the dips observed in Kepler-1229's light curve, thus confirming it as a planet. The planet was then announced in the newest catalog released by NASA on May 12, 2016, about 3 years later.^[9]

At nearly 770 light-years (236 pc) distant, Kepler-1229b is too remote and its star too far for current telescopes or the next generation of planned telescopes to determine its mass or whether it has an atmosphere. The Kepler spacecraft focused on a single small region of the sky but next-generation planet-hunting space telescopes, such asTESS andCHEOPS, will examine nearby stars throughout the sky. Nearby stars with planets can then be studied by the upcomingJames Webb Space Telescope and future large ground-based telescopes to analyze atmospheres, determine masses and infer compositions. Additionally theSquare Kilometer Array would significantly improve radio observations over theArecibo Observatory andGreen Bank Telescope.^[10]

• List of potentially habitable exoplanets
• Kepler-62f – similar exoplanet with around the same radius and stellar flux.

• Exoplanets discovered by the Kepler space telescope
• Exoplanets discovered in 2016
• Exoplanets in the habitable zone
• Transiting exoplanets
• Super-Earths in the habitable zone
• Cygnus (constellation)
• Kepler-1229

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