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Entering orbit…
Habitability
32/ 100
Extremely Harsh
Kepler-186 f rendered in TerraForge from its measured mass, orbit and star

Kepler-186 f

Also written Kepler-186f, Kepler 186f, Kepler 186 f

Ice World580 light years awayFound 2014
Mass
1.71 × Earth
Radius
1.17 × Earth
Gravity
1.25 g
Surface (est.)
208 K
Year
130 days
From Earth
581 ly
Mass
1.71 × Earth
Radius
1.17 × Earth
Gravity
1.25 g
Surface (est.)
208 K
Year
130 days
From Earth
581 ly

Kepler-186 system

Type
K-type (Orange)
Spectral type
M1
Temperature
3,755 K
Radius
0.523 ☉
Mass
0.544 ☉
Planets
5
Luminosity
0.0550 ☉

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-186 b0.034 AU1.2 M⊕
Kepler-186 c0.045 AU2.1 M⊕
Kepler-186 d0.078 AU2.5 M⊕
Kepler-186 e0.11 AU2.1 M⊕
Kepler-186 f0.43 AUYou are here1.7 M⊕
Habitable zone

Star and planets drawn to scale: the star is 49 times as wide as Kepler-186 f, so only its edge is in view. Orbits spaced as in the star system view.

In April 2014 Kepler-186 f became the first Earth-size planet found in the habitable zone of another star, the range of distances where liquid water could pool on a surface. NASA's Kepler space telescope caught it passing in front of its star. A team led by Elisa Quintana of the SETI Institute at NASA's Ames Research Center announced it. Earlier habitable-zone planets were all at least 40 percent larger than Earth.

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

Ice World
Life unlikely — too cold for liquid waterMagnetic FieldModerate Activity
Kepler-186 f orbits at 0.43 AU from its star, resulting in frigid temperatures of 208K.
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: 0.43 AU (>3 AU) or Temperature <200K✓ Temperature: 208K✓ Water content: 35.0% for ice formation

Reading Kepler-186 f’s atmosphere

Dominant elements: O, Si, Fe, N, H, CThis is what a telescope would measure while Kepler-186 f 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-186 f sits about 581 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.
As an Amazon Associate I earn from qualifying purchases — if you buy through these links, TerraForge may receive a small commission at no extra cost to you.
Habitability ScoreExtremely Harsh
32
Contributing Factors
temperature24
Extreme cold - very difficult for life
atmosphere70

Thin nitrogen and methane atmosphere

Nitrogen atmosphere provides protection but not breathable
water23
Limited water content - 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
1.71x Earth (1.02e+25 kg)
Radius
1.20x Earth (7,619 km)
This planet: 1.20× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.20x Earth (11.7 m/s²)
Surface Temperature
208 K (-65 °C / -85 °F)
Rotation Period
24.0 hours/day
This planet: 24 h/dayEarth: 24 h/day

Elemental Composition

How TerraForge built this world

Kepler-186 f, from the NASA Exoplanet Archive (found 2014). Measured: 1.71 Earth masses, 0.432 AU, a 3755 K K-type star. Composition inferred from a measured bulk density of 1.07x Earth's, which is rock and iron, with an assumed 24-hour day — rotation cannot be measured for exoplanets.

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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