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Entering orbit…
Habitability
50/ 100
Marginal

Kepler-138 e

Rocky TerrestrialMarginal218 light years awayFound 2022

Kepler-138 e, from the NASA Exoplanet Archive (found 2022). Measured: 0.43 Earth masses, 0.18 AU, a 3841 K K-type star. Composition inferred from a measured bulk density of 0.85x Earth's, which is rock and iron, with an assumed 24-hour day — rotation cannot be measured for exoplanets.

Host star

Kepler-138

Type
K-type (Orange)
Spectral type
M1 V
Temperature
3,841 K
Radius
0.535 ☉
Mass
0.535 ☉
Known planets
4, including this one
Luminosity
0.0560 ☉

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.

Rocky Terrestrial

Life DetectedLow Activity
Why is this a Rocky Terrestrial?Your planet is dominated by silicate (25.0%) and iron (12.5%) content, forming a rocky terrestrial body.
Rocky terrestrial planets are primarily composed of silicate rocks and metals. They're the most common type of small planet in the universe.
Classification Criteria:
✓ Silicon: 25.0% + Iron: 12.5% + Magnesium: 3.8%✓ Mass: 0.4x Earth (terrestrial range)
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
50
Contributing Factors
temperature70
Challenging but potentially habitable temperature
atmosphere70
Nitrogen atmosphere provides protection but not breathable
water35
Limited water content (low gravity lets water escape to space)
magnetic Field30
No magnetic field - vulnerable to solar radiation
geology60
Some geological activity provides slow nutrient cycling
Organic Chemistry80
Core organic elements (CHNO) present
rotation100
Optimal rotation period - balanced day/night cycle, moderate weather, and good heat distribution

Physical Properties

Mass
0.43x Earth (2.57e+24 kg)
Radius
0.75x Earth (4,809 km)
This planet: 0.75× Earth radiusEarth: 1× (baseline)
Surface Gravity
0.75x Earth (7.4 m/s²)
Surface Temperature
322 K (49 °C / 120 °F)
Rotation Period
24.0 hours/day
This planet: 24 h/dayEarth: 24 h/day

Orbital Environment

Star Type
K-type (Orange)
Distance from Star
0.18 AU (26.9 million km)
Orbital Period
33 days

Atmosphere

Thin CO₂ and nitrogen atmosphere

Elemental Composition

O - Oxygen
31.3%
Si - Silicon
25.0%
Fe - Iron
12.5%

Surface Characteristics

Rocky surface with impact craters, possible volcanic features

Habitability

✓ Conditions suitable for life detectedThis planet exhibits the necessary conditions to support biological processes, including stable temperatures, liquid water, and protective magnetic fields.
The TerraForge exoplanet catalog: 5,572 real exoplanets run through the simulation, with a search field and rendered worlds grouped by type

New: The Exoplanet Catalog 🔭

Every confirmed planet NASA has measured well enough to build — 5,572 of them — is now in here, and none of them arrived with a label. Their real mass, radius, orbit and star go through the same simulation that runs everything you make, and it decides what each one is: gas giant, lava world, ocean, ice. Sixteen come out Earth-like. Find TRAPPIST-1e, stand on its surface, and see what a red dwarf's light actually looks like from the ground.

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