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
0/ 100
Uninhabitable

HD 156668 b

Lava WorldUninhabitable79 light years awayFound 2010

HD 156668 b, from the NASA Exoplanet Archive (found 2010). Measured: 4.15 Earth masses, 0.05 AU, a 4850 K K-type star. Composition inferred from a measured bulk density of 0.63x Earth's — too light for bare rock, so a large fraction of water and ice, with a day locked to its 4.7-day year, as anything orbiting this close would be. Note: TerraForge comes out at 1501 K against the archive's 887 K, because it models stars by spectral class, and HD 156668 is not an average K-type.

Host star

HD 156668

Type
K-type (Orange)
Spectral type
K2
Temperature
4,850 K
Radius
0.72 ☉
Mass
0.772 ☉
Known planets
2, including this one
Luminosity
1.70 ☉

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.

Lava World

Extreme Activity
Why is this a Lava World?Your planet's proximity to its star (0.05 AU) results in extreme surface temperatures of 1501K.
Lava worlds orbit so close to their stars that rocky surfaces melt into oceans of molten rock. Recent planet formation can also create temporary lava worlds.
Classification Criteria:
✓ Temperature: 1501K (>1000K)
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.Imagined LifeJames Trefil & Michael SummersWhat could live on a world like this one: ice shells, supergravity, tidally locked twilight.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.
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 ScoreUninhabitable
0
Contributing Factors
temperature0
Inferno world - temperatures exceed all possibility of life
atmosphere10
No atmosphere - exposed to radiation and temperature extremes
water15
Abundant water - boiling away, little would be retained
magnetic Field30
No magnetic field - vulnerable to solar radiation
geology40
Extreme volcanic activity may be hazardous
Organic Chemistry80
Core organic elements (CHNO) present
rotation30
Very slow rotation - extreme temperature swings between eternal day and night sides

Physical Properties

Mass
4.15x Earth (2.48e+25 kg)
Radius
1.61x Earth (10,238 km)
This planet: 1.61× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.61x Earth (15.8 m/s²)
Surface Temperature
1,501 K (1,228 °C / 2,242 °F)
Rotation Period
111.6 hours/day (slower than Earth)
This planet: 112 h/dayEarth: 24 h/day

Orbital Environment

Star Type
K-type (Orange)
Distance from Star
0.05 AU (7.48 million km)
Orbital Period
5 days
Time Dilation
Clocks run 6.5 seconds per year slower than deep space — about 9 minutes over a lifetime

Atmosphere

Minimal - too hot to retain

Elemental Composition

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

Surface Characteristics

Molten surface with lava flows, volcanic activity everywhere
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