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Entering orbit…
Habitability
55/ 100
Marginal
GJ 667 C f rendered in TerraForge from its measured mass, orbit and star

GJ 667 C f

Also written GJ 667 Cf

Ice World24 light years awayFound 2013
Mass
2.70 × Earth
Radius
1.45 × Earth
Gravity
1.28 g
Surface (est.)
244 K
Year
39.0 days
From Earth
23.6 ly
Mass
2.70 × Earth
Radius
1.45 × Earth
Gravity
1.28 g
Surface (est.)
244 K
Year
39.0 days
From Earth
23.6 ly

GJ 667 C system

Type
M-type (Red Dwarf)
Spectral type
M1.5 V
Temperature
3,350 K
Mass
0.33 ☉
Planets
5
Luminosity
0.0137 ☉

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.

GJ 667 C b0.050 AU5.7 M⊕
GJ 667 C c0.13 AU3.8 M⊕
GJ 667 C f0.16 AUYou are here2.7 M⊕
GJ 667 C e0.21 AU2.7 M⊕
GJ 667 C g0.55 AU4.6 M⊕
Habitable zone

Planets drawn to scale with each other; the star's size is not measured. Orbits spaced as in the star system view.

Estimated: this planet doesn't transit its star, so its size is inferred, not measured

GJ 667 C f is a proposed planet whose existence is disputed. It was reported in 2013 as one of up to seven planets around GJ 667 C, a red dwarf about 24 light-years away in a triple star system. In that model it orbits every 39 days, just outside its sibling GJ 667 C c, and has a minimum mass of about 2.7 Earth masses.

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
GJ 667 C f orbits at 0.16 AU from its star, resulting in frigid temperatures of 244K.
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: 0.16 AU (>3 AU) or Temperature <200K✓ Temperature: 244K✓ Water content: 34.4% for ice formation

Reading GJ 667 C f’s atmosphere

Dominant elements: O, Si, Fe, N, C, HThis is what a telescope would measure while GJ 667 C 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.GJ 667 C f sits about 24 light-years away, found by the radial velocity 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
55
Contributing Factors
temperature43
Cold - water freezes much of the year; challenging but potentially habitable
atmosphere70

Thin nitrogen and methane atmosphere

Nitrogen atmosphere provides protection but not breathable
water38
Limited water content - mostly frozen
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
2.70x Earth (1.61e+25 kg)
Radius
1.39x Earth (8,871 km)
This planet: 1.39× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.39x Earth (13.7 m/s²)
Surface Temperature
244 K (-29 °C / -20 °F)
Rotation Period
24.0 hours/day
This planet: 24 h/dayEarth: 24 h/day

Elemental Composition

How TerraForge built this world

GJ 667 C f, from the NASA Exoplanet Archive (found 2013). Measured: 2.7 Earth masses, 0.156 AU, a 3350 K M-type star. Composition inferred from an estimated bulk density of 0.89x Earth's, modeled rather than measured since this isn't a transiting planet — the radius is the archive's estimate, so it can't settle how much water there is; read as 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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