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Entering orbit…
Habitability
0/ 100
Uninhabitable

K2-138 f

Gas WispUninhabitable662 light years awayFound 2017

K2-138 f, from the NASA Exoplanet Archive (found 2017). Measured: 1.63 Earth masses, 0.104 AU, a 5356 K G-type star. Composition inferred from a measured bulk density of 0.07x Earth's, which only hydrogen and helium can explain, with an assumed 24-hour day — rotation cannot be measured for exoplanets.

Host star

K2-138

Type
G-type (Yellow (Sun-like))
Spectral type
G8 V
Temperature
5,356 K
Radius
0.863 ☉
Mass
0.935 ☉
Known planets
6, including this one
Luminosity
0.517 ☉

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.

Gas Wisp

None Activity
Why is this a Gas Wisp?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: 1.6x EarthTemperature: 733K
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.
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Habitability ScoreUninhabitable
0
Contributing Factors
temperature5
Scorching - hot enough to melt lead, though rock stays solid; no chance for life
atmosphere10
No atmosphere - exposed to radiation and temperature extremes
water15
No solid surface — any water is locked in a supercritical mantle and hot ice, not oceans
magnetic Field30
No magnetic field - vulnerable to solar radiation
geology30
Geologically dead - no nutrient recycling
Organic Chemistry80
Core organic elements (CHNO) present
rotation100
Optimal rotation period - balanced day/night cycle, moderate weather, and good heat distribution

Physical Properties

Mass
1.63x Earth (9.73e+24 kg)
Radius
1.18x Earth (7,498 km)
This planet: 1.18× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.18x Earth (11.5 m/s²)
Surface Temperature
733 K (460 °C / 859 °F)
Rotation Period
24.0 hours/day
This planet: 24 h/dayEarth: 24 h/day

Orbital Environment

Star Type
G-type (Yellow (Sun-like))
Distance from Star
0.10 AU (15.6 million km)
Orbital Period
12 days

Atmosphere

None

Elemental Composition

H - Hydrogen
53.8%
He - Helium
32.3%
O - Oxygen
5.4%

Surface Characteristics

No planet ever formed: too little gravity to bind the light gases - the cloud dispersed into a thin drifting wisp
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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