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Entering orbit…
Habitability
43/ 100
Marginal

GJ 251 b

BarrenMarginal18 light years awayFound 2020

GJ 251 b, from the NASA Exoplanet Archive (found 2020). Measured: 3.85 Earth masses, 0.0808 AU, a 3342 K M-type star. Composition inferred from a measured bulk density of 0.67x Earth's — too light for bare rock, so a large fraction of water and ice, with a day locked to its 14.2-day year, as anything orbiting this close would be.

Host star

GJ 251

Type
M-type (Red Dwarf)
Spectral type
M3.0 V
Temperature
3,342 K
Radius
0.36 ☉
Mass
0.35 ☉
Known planets
2, including this one
Luminosity
0.0155 ☉

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.

Barren

High Activity
Why is this a Barren?Your planet has an unusual composition that doesn't fit standard classifications, or lacks the elements needed for complex geological processes.
Barren worlds can form from uncommon element combinations or may be remnants of larger bodies that lost their atmospheres and volatile materials.
Classification Criteria:
Composition doesn't match standard planet typesMass: 3.9x EarthTemperature: 371K
Further reading
The Little Book of ExoplanetsJoshua WinnHow these worlds are found, and what a measurement can honestly tell us.Exoplanets: Diamond Worlds, Super Earths, Pulsar PlanetsMichael Summers & James TrefilThe strange end of the catalogue — carbon worlds, molten rock, planets orbiting dead stars.Envisioning ExoplanetsMichael CarrollWhat these worlds might look like from the ground, painted from the same measurements this page renders.Imagined LifeJames Trefil & Michael SummersWhat could live on a world like this one: ice shells, supergravity, tidally locked twilight.
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 ScoreMarginal
43
Contributing Factors
temperature40
Extreme temperature - very difficult for life
atmosphere42
Nitrogen atmosphere provides protection but not breathable (partially stripped by slow rotation)
water100
Abundant water
magnetic Field30
No magnetic field - vulnerable to solar radiation
geology90
Active geology recycles nutrients and drives carbon cycle
Organic Chemistry80
Core organic elements (CHNO) present
rotation30
Very slow rotation - extreme temperature swings between eternal day and night sides

Physical Properties

Mass
3.85x Earth (2.30e+25 kg)
Radius
1.57x Earth (9,985 km)
This planet: 1.57× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.57x Earth (15.4 m/s²)
Surface Temperature
371 K (98 °C / 209 °F)
Rotation Period
340.8 hours/day (slower than Earth)
This planet: 341 h/dayEarth: 24 h/day

Orbital Environment

Star Type
M-type (Red Dwarf)
Distance from Star
0.08 AU (12.1 million km)
Orbital Period
15 days

Atmosphere

Thin CO₂ and nitrogen atmosphere

Elemental Composition

O - Oxygen
41.2%
H - Hydrogen
17.6%
Si - Silicon
11.8%

Surface Characteristics

Barren rocky surface with unusual elemental composition
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