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. Read our privacy policy.
Entering orbit…
Habitability
0/ 100
Uninhabitable
Wolf 940 b rendered in TerraForge from its measured mass, orbit and star

Wolf 940 b

Also written Wolf 940b

Brown DwarfUninhabitable41 light years awayFound 2009
exoplanet.euListed by the Extrasolar Planets Encyclopaedia; not yet in NASA's confirmed catalogue.View on exoplanet.eu

Estimated: this planet doesn't transit its star, so its size is inferred, not measured

Wolf 940 b, from the Extrasolar Planets Encyclopaedia (found 2009). Measured: 8260 Earth masses, 400 AU, a 3200 K M-type star. Composition inferred from a mass of 8260 Earths, which is giant territory whatever its 7.56x density suggests, with an assumed 24-hour day — rotation cannot be measured for exoplanets.

Host star

Wolf 940

Type
M-type (Red Dwarf)
Spectral type
M4V
Temperature
3,200 K
Mass
0.27 ☉
Known planets
1 (this one)

Published by the Extrasolar Planets Encyclopaedia. This star’s luminosity has not been published, so this world’s temperature and habitability score fall back to a typical M-type star.

Brown Dwarf

Magnetic FieldNone Activity
Why is this a Brown Dwarf?
Wolf 940 b 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: 8260.0x EarthTemperature: 1672K

Reading Wolf 940 b’s atmosphere

Dominant elements: H, He, O, C, NThis is what a telescope would measure while Wolf 940 b crosses in front of its star: starlight passes through the atmosphere and spreads into a rainbow band. Each dark line marks a wavelength the atmosphere absorbed.Every element absorbs its own signature wavelengths — hydrogen always darkens the same two spots, calcium another pair, and so on. Astronomers match the lines in a real spectrum against a library of these signatures to say what an atmosphere is made of, light-years away, without ever visiting. A deeper line generally means more of that element is present.Wolf 940 b sits about 41 light-years away, found by the imaging method. Most catalogued distances trace back to parallax: as Earth orbits the Sun, a nearby star appears to shift very slightly against the distant background stars, and the size of that shift gives its distance directly.
Further reading
ExoplanetsSara Seager (editor)The field's standard reference: how planets are found, how they form, and what their atmospheres are made of.The Planet FactoryElizabeth TaskerHow planets are made, and why so few of them come out like Earth.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.
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
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 Field20
A strong field, but no surface beneath it — there is nothing here for it to shelter
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
8260.00x Earth (4.93e+28 kg)
Radius
20.21x Earth (128,786 km)
This planet: 20.21× Earth radiusEarth: 1× (baseline)
Surface Gravity
20.21x Earth (198.3 m/s²)
Surface Temperature
1,672 K (1,399 °C / 2,550 °F)
Rotation Period
24.0 hours/day
This planet: 24 h/dayEarth: 24 h/day

Orbital Environment

Star Type
M-type (Red Dwarf)
Distance from Star
400.00 AU (59.8 billion km)
Orbital Period
14,606 years

Atmosphere

Hydrogen and helium with iron and silicate cloud decks - hot enough to rain molten metal

Elemental Composition

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

Surface Characteristics

No surface: a deuterium-burning sphere the size of Jupiter and dozens of times its mass, glowing dull red from its own heat
Love TerraForge? Please help support us.Keeps it ad-free, and funds new features and hosting.
The surface of TOI-700 d as TerraForge draws it: red-leaved trees over green ground under a lavender sky

New: Stand on a Planet in VR 🥽

Open any planet's surface view on your phone and look around just by moving it: hold it up, turn on the spot, and the view turns with you. In Chrome on Android you also get a VR button, in the row along the bottom:

The surface view's bottom row of buttons on a phone, with an arrow pointing to the VR button beside full screen

Tap it, drop your phone into a headset viewer, and you're standing on the ground under a star that isn't ours. It only appears where your browser can do VR.

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. Read our privacy policy.

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
Idea
Bug
Pain point
Other