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Entering orbit…
Habitability
34/ 100
Extremely Harsh
LHS 1140 b rendered in TerraForge from its measured mass, orbit and star

LHS 1140 b

Also written LHS 1140b

Ice World49 light years awayFound 2017
Mass
5.60 × Earth
Radius
1.73 × Earth
Gravity
1.87 g
Surface (est.)
234 K
Year
24.7 days
From Earth
48.9 ly
Mass
5.60 × Earth
Radius
1.73 × Earth
Gravity
1.87 g
Surface (est.)
234 K
Year
24.7 days
From Earth
48.9 ly

LHS 1140 system

Type
M-type (Red Dwarf)
Spectral type
M4.5 V
Temperature
3,096 K
Radius
0.216 ☉
Mass
0.184 ☉
Planets
2
Luminosity
3.80e-3 ☉

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.

LHS 1140 c0.027 AU1.9 M⊕
LHS 1140 b0.095 AUYou are here5.6 M⊕
Habitable zone

Star and planets drawn to scale: the star is 14 times as wide as LHS 1140 b, so only its edge is in view. Orbits spaced as in the star system view.

Ice World, likely · its density could also fit a sub-Neptune

Some researchers have called LHS 1140 b the best current chance to study a potentially habitable world beyond the solar system. A team led by Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics announced it in 2017. The MEarth telescopes caught it passing in front of its star, a small red dwarf about 49 light-years away. The HARPS spectrograph in Chile then confirmed it by measuring how the planet tugs its star back and forth. It orbits every 25 days inside the habitable zone, where liquid water could exist.

Surface. Frozen surface covered in water ice, possible subsurface ocean if tidal heating present

Ice World
Life unlikely — too cold for liquid waterHigh Activity
LHS 1140 b orbits at 0.09 AU from its star, resulting in frigid temperatures of 234K.
Ice worlds form beyond the frost line where temperatures are low enough for water and other volatiles to freeze solid. They may have subsurface oceans beneath thick ice shells.
Classification Criteria:
✓ Distance: 0.09 AU (>3 AU) or Temperature <200K✓ Temperature: 234K✓ Water content: 38.3% for ice formation

Reading LHS 1140 b’s atmosphere

Dominant elements: O, Si, H, Fe, N, CThis is what a telescope would measure while LHS 1140 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.LHS 1140 b sits about 49 light-years away, found by the transit 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.Imagined LifeJames Trefil & Michael SummersWhat could live on a world like this one: ice shells, supergravity, tidally locked twilight.Envisioning ExoplanetsMichael CarrollWhat these worlds might look like from the ground, painted from the same measurements this page renders.
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Habitability ScoreExtremely Harsh
34
Contributing Factors
temperature36
Extreme cold - very difficult for life
atmosphere28

Thin nitrogen and methane atmosphere

Nitrogen atmosphere provides protection but not breathable (partially stripped by slow rotation)
water61
Good water content - mostly frozen
magnetic Field30
No magnetic field - vulnerable to solar radiation
geology90
Active geology recycles nutrients and drives carbon cycle
Organic Chemistry80
Core organic elements (CHNO) present
rotation10
Near tidally locked - one hemisphere perpetually scorched, other frozen, narrow habitable twilight zone only

Physical Properties

Mass
5.60x Earth (3.34e+25 kg)
Radius
1.78x Earth (11,314 km)
This planet: 1.78× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.78x Earth (17.4 m/s²)
Surface Temperature
234 K (-39 °C / -38 °F)
Rotation Period
592.8 hours/day (slower than Earth)
This planet: 593 h/dayEarth: 24 h/day

Elemental Composition

How TerraForge built this world

LHS 1140 b, from the NASA Exoplanet Archive (found 2017). Measured: 5.6 Earth masses, 0.0946 AU, a 3096 K M-type star. Composition inferred from a measured bulk density of 1.08x Earth's at this size, suggesting roughly 14% water/ice by mass, with a day locked to its 24.7-day year, as anything orbiting this close would be.

A dark ringed planet hanging over the horizon of a rocky moon, its rings lit by a distant sun

New: Stand on Your Moons 🌒

A planet's surface view isn't the only ground any more. Press the surface button on a planet with moons and it asks where to stand: the planet itself, or any moon still in orbit, each tagged with what it became — ocean, ice, carbon, volcanic. Every moon gets its own ground and sky from its own physics: airless rock under a black sky, ice cracked by geysers over a hidden sea, sulfur plains shaking with eruptions, or orange haze you can't see the sun through. And hanging over the horizon, there's the planet you built.

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