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Kepler-1229 b

Kepler-1229 · M1V host star · cool red dwarf · main sequence

[ KEPLER_1229_B.IMG ]
VIEW 1 · ON THE SURFACE
1 / 2
Artist’s impression of Kepler-1229 b: VIEW 1 · ON THE SURFACE
VIEW 1 · ON THE SURFACE · Artist’s impression. No surface has been seen.
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865.9 light-years from Earth
[ FACTS.DAT ]
Right ascension / declination297.487° / 46.997°J2000 / ICRS
Gravity1.30 × Earthmodelled estimate
Year86.8 days
From its star0.3006 AUabout 45.0 million km
Stars in the system1 star1 known planet in system
Stars this world orbits1 starOrbits Kepler-1229
Day and nightSpin state unknownIts rotation has not been measured, so we do not know whether it has a normal day/night cycle. Heuristic: likely at ≤0.25 AU, uncertain to 0.50 AU, probably not beyond; rotation is not directly measured.
[ TEMP.EST ]MODELLED, NOT MEASURED
Host star≈3,700 Ktypical M1V · 0.50 Sun radii
No atmosphere210 K · -63°C30% reflective · heat shared
Earth-like air243 K · -30°CBaseline plus 33°C

Star temperature and orbital distance set incoming energy, but stellar size is also required. This calculation uses a typical radius for the listed spectral type, 30% reflectivity and even heat redistribution. It is not a ground-temperature forecast: air, clouds, oceans and surface reflectivity could move the result by tens to hundreds of degrees.

[ STARLIGHT.SPC ]VISIBLE LIGHT ONLY

The marker above the bar is a typical temperature for this star’s class. The line below is Earth’s Sun.

red-orange

Kepler-1229 is class M1V. Its visible daylight would be dim and strongly red-orange; most of its energy is infrared.

Representative daytime geometry only; the star’s height in the sky changes through the day.

[ GROUND.TXT ]STILL INFERENCE

Most plausible case. A 0.30 AU orbit, 87 days, around a 0.51-solar-radius star at 3784 K. The star spans about 0.9°, and the planet receives about half of Earth’s light. That is cooler than the close-in M-dwarf eyeballs. The spin is uncertain at this distance. Rock and frost, with ice more widespread than on a 1.4-times-Earth-flux world. Radius 1.40 Earth radii, mass modelled.

Dry case. Cold rock and dust. A thin sky does not make a hot desert at half of Earth’s light.

Thick-air case. CO₂ greenhouse and cloud. That is the temperate version of this orbit, and it hides the ground.

Walking. About 30% heavier than Earth, modelled. No known neighbor planet. The daylight is orange-red and half of Earth’s energy, under a star a bit under twice the Sun’s width. Magnitude 16, about 870 light-years away.

Based on: NASA composite; Teff 3784 K, R 0.51 Rsun, S 0.52, Rp 1.40, a 0.301 AU

[ ORBIT.SYS ]1 KNOWN · ALL SHOWN
100% · Above 30°

Kepler-1229 b circles Kepler-1229. Use Higher and Lower to move your viewpoint above, through and below the orbital plane, and − / + to zoom. Orbit shapes and spacing are schematic.

[ SOURCES.TXT ]

Positions, distances, and system parameters come from the NASA Exoplanet Archive composite table, queried 25 Sep 2026. GJ 273 b uses the parallax in that row, 12.4 light-years. The 45 worlds follow Bohl, Lawrence, Lowry, and Kaltenegger.