Create your free account

Enter your email and we'll send a 6-digit code — no password needed.
We only keep your email and the username you choose. We never share or sell your email, and we don't send marketing — we use it only to email you a sign-in code. Learn more.
Entering orbit…
Habitability
28/ 100
Extremely Harsh

Kepler-51 d

Gas DwarfExtremely Harsh2556 light years awayFound 2014

Kepler-51 d, from the NASA Exoplanet Archive (found 2014). Measured: 7.6 Earth masses, 0.509 AU, a 6018 K F-type star. Composition inferred from a measured bulk density of 0.01x Earth's, which only hydrogen and helium can explain, with an assumed 24-hour day — rotation cannot be measured for exoplanets.

Host star

Kepler-51

Type
F-type (White)
Temperature
6,018 K
Radius
0.94 ☉
Mass
1.04 ☉
Known planets
4, including this one
Luminosity
0.722 ☉

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 Dwarf

Magnetic FieldLow Activity
Why is this a Gas Dwarf?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: 7.6x EarthTemperature: 360K
Further reading
Exoplanets: Diamond Worlds, Super Earths, Pulsar PlanetsMichael Summers & James TrefilThe strange end of the catalogue — carbon worlds, molten rock, planets orbiting dead stars.The Little Book of ExoplanetsJoshua WinnHow these worlds are found, and what a measurement can honestly tell us.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 ScoreExtremely Harsh
28
Contributing Factors
temperature40
Extreme temperature - very difficult for life
atmosphere30
Hydrogen-rich atmosphere typical of gas giants
water15
No solid surface — any water is locked in a supercritical mantle and hot ice, not oceans
magnetic Field100
Magnetic field provides radiation protection
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
7.60x Earth (4.54e+25 kg)
Radius
1.97x Earth (12,526 km)
This planet: 1.97× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.97x Earth (19.3 m/s²)
Surface Temperature
360 K (87 °C / 188 °F)
Rotation Period
24.0 hours/day
This planet: 24 h/dayEarth: 24 h/day

Orbital Environment

Star Type
F-type (White)
Distance from Star
0.51 AU (76.1 million km)
Orbital Period
116 days

Atmosphere

Deep hydrogen-helium envelope with photochemical haze

Elemental Composition

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

Surface Characteristics

No solid surface - a thick gas envelope wrapped around a small deep core (a mini-Neptune)
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.

Create your free account

Enter your email and we'll send a 6-digit code — no password needed.
We only keep your email and the username you choose. We never share or sell your email, and we don't send marketing — we use it only to email you a sign-in code. Learn more.

Send feedback

We're still building out the best experience we can — and we'd love your input. Tell us about features you enjoy, ideas you'd like to see, or pain points where something feels off, and we'll know where to look next.

Type