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Entering orbit…
Habitability
54/ 100
Marginal
Kepler-1229 b rendered in TerraForge from its measured mass, orbit and star

Kepler-1229 b

Also written Kepler-1229b, Kepler 1229b, Kepler 1229 b

Ice World864 light years awayFound 2016
Mass
2.54 × Earth
Radius
1.40 × Earth
Gravity
1.30 g
Surface (est.)
219 K
Year
86.8 days
From Earth
864 ly
Mass
2.54 × Earth
Radius
1.40 × Earth
Gravity
1.30 g
Surface (est.)
219 K
Year
86.8 days
From Earth
864 ly

Kepler-1229 system

Type
K-type (Orange)
Temperature
3,784 K
Radius
0.51 ☉
Mass
0.54 ☉
Planets
1
Luminosity
0.0293 ☉

Published by the NASA Exoplanet Archive. This world’s temperature and habitability score are computed from this star’s measured luminosity, not from a stand-in for its class.

Kepler-1229 b0.30 AUYou are here2.5 M⊕
Habitable zone

Star and planets drawn to scale: the star is 40 times as wide as Kepler-1229 b, so only its edge is in view. Orbits spaced as in the star system view.

Ice World, likely · its density could also fit a sub-Neptune

Kepler-1229 b, from the NASA Exoplanet Archive (found 2016). Measured: 2.54 Earth masses, 0.301 AU, a 3784 K K-type star. Composition inferred from a measured bulk density of 0.93x Earth's at this size, suggesting roughly 16% water/ice by mass, with an assumed 24-hour day — rotation cannot be measured for exoplanets.

Surface. Frozen surface covered in water ice, possible subsurface ocean if tidal heating present

Ice World
Life unlikely — too cold for liquid waterMagnetic FieldHigh Activity
Kepler-1229 b orbits at 0.30 AU from its star, resulting in frigid temperatures of 219K.
Ice worlds form beyond the frost line where temperatures are low enough for water and other volatiles to freeze solid. They may have subsurface oceans beneath thick ice shells.
Classification Criteria:
✓ Distance: 0.30 AU (>3 AU) or Temperature <200K✓ Temperature: 219K✓ Water content: 38.8% for ice formation

Reading Kepler-1229 b’s atmosphere

Dominant elements: O, Si, H, Fe, N, CThis is what a telescope would measure while Kepler-1229 b crosses in front of its star: starlight passes through the atmosphere and spreads into a rainbow band. Each dark line marks a wavelength the atmosphere absorbed.Every element absorbs its own signature wavelengths — hydrogen always darkens the same two spots, calcium another pair, and so on. Astronomers match the lines in a real spectrum against a library of these signatures to say what an atmosphere is made of, light-years away, without ever visiting. A deeper line generally means more of that element is present.Kepler-1229 b sits about 864 light-years away, found by the transit method. Most catalogued distances trace back to parallax: as Earth orbits the Sun, a nearby star appears to shift very slightly against the distant background stars, and the size of that shift gives its distance directly.
Further reading
ExoplanetsSara Seager (editor)The field's standard reference: how planets are found, how they form, and what their atmospheres are made of.The Planet FactoryElizabeth TaskerHow planets are made, and why so few of them come out like Earth.Imagined LifeJames Trefil & Michael SummersWhat could live on a world like this one: ice shells, supergravity, tidally locked twilight.Envisioning ExoplanetsMichael CarrollWhat these worlds might look like from the ground, painted from the same measurements this page renders.
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Habitability ScoreMarginal
54
Contributing Factors
temperature29
Extreme cold - very difficult for life
atmosphere70

Thin nitrogen and methane atmosphere

Nitrogen atmosphere provides protection but not breathable
water55
Abundant water - frozen solid, no liquid phase at this temperature
magnetic Field100
Magnetic field provides radiation protection
geology90
Active geology recycles nutrients and drives carbon cycle
Organic Chemistry80
Core organic elements (CHNO) present
rotation100
Optimal rotation period - balanced day/night cycle, moderate weather, and good heat distribution

Physical Properties

Mass
2.54x Earth (1.52e+25 kg)
Radius
1.36x Earth (8,693 km)
This planet: 1.36× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.36x Earth (13.4 m/s²)
Surface Temperature
219 K (-54 °C / -65 °F)
Rotation Period
24.0 hours/day
This planet: 24 h/dayEarth: 24 h/day

Elemental Composition

A dark ringed planet hanging over the horizon of a rocky moon, its rings lit by a distant sun

New: Stand on Your Moons 🌒

A planet's surface view isn't the only ground any more. Press the surface button on a planet with moons and it asks where to stand: the planet itself, or any moon still in orbit, each tagged with what it became — ocean, ice, carbon, volcanic. Every moon gets its own ground and sky from its own physics: airless rock under a black sky, ice cracked by geysers over a hidden sea, sulfur plains shaking with eruptions, or orange haze you can't see the sun through. And hanging over the horizon, there's the planet you built.

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