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Entering orbit…
Habitability
42/ 100
Marginal
TRAPPIST-1 e rendered in TerraForge from its measured mass, orbit and star

TRAPPIST-1 e

Also written TRAPPIST-1e, TRAPPIST 1e, TRAPPIST 1 e

Rocky Terrestrial40 light years awayFound 2017
Mass
0.69 × Earth
Radius
0.92 × Earth
Gravity
0.82 g
Surface (est.)
253 K
Year
6.1 days
From Earth
40.4 ly
Mass
0.69 × Earth
Radius
0.92 × Earth
Gravity
0.82 g
Surface (est.)
253 K
Year
6.1 days
From Earth
40.4 ly

TRAPPIST-1 system

Type
M-type (Red Dwarf)
Spectral type
M8.0 V
Temperature
2,566 K
Radius
0.119 ☉
Mass
0.0898 ☉
Planets
7
Luminosity
5.53e-4 ☉

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.

TRAPPIST-1 b0.011 AU1.4 M⊕
TRAPPIST-1 c0.016 AU1.3 M⊕
TRAPPIST-1 d0.022 AU0.4 M⊕
TRAPPIST-1 e0.029 AUYou are here0.7 M⊕
TRAPPIST-1 f0.038 AU1.0 M⊕
TRAPPIST-1 g0.047 AU1.3 M⊕
TRAPPIST-1 h0.062 AU0.3 M⊕
Habitable zone

Star and planets drawn to scale: the star is 14 times as wide as TRAPPIST-1 e, so only its edge is in view. Orbits spaced as in the star system view.

TRAPPIST-1 e is one of very few rocky planets that both sits in its star's habitable zone and can be studied in detail by the James Webb Space Telescope. The habitable zone is the range of distances where, with the right atmosphere, liquid water could last on a planet's surface. Planet e is close to Earth in size, about 0.92 times its width and 0.69 times its mass, and it circles its small red star every 6.1 days.

Surface. Rocky surface with impact craters, possible volcanic features

✓ Conditions could support life. This planet’s modelled conditions could support biological processes: stable temperatures, liquid water and the chemistry life as we know it needs. That makes life possible, not present.

Rocky Terrestrial
Life possibleLow Activity
TRAPPIST-1 e is dominated by silicate (24.3%) and iron (12.1%) content, forming a rocky terrestrial body.
Rocky terrestrial planets are primarily composed of silicate rocks and metals. They're the most common type of small planet in the universe.
Classification Criteria:
✓ Silicon: 24.3% + Iron: 12.1% + Magnesium: 3.6%✓ Mass: 0.7x Earth (terrestrial range)

Reading TRAPPIST-1 e’s atmosphere

Dominant elements: O, Si, Fe, N, H, CThis is what a telescope would measure while TRAPPIST-1 e 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.TRAPPIST-1 e sits about 40 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.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 ScoreMarginal
42
Contributing Factors
temperature60
Cold - water freezes much of the year; challenging but potentially habitable
atmosphere70

Thin CO₂ and nitrogen atmosphere

Nitrogen atmosphere provides protection but not breathable
water42
Limited water content - mostly frozen (low gravity lets water escape to space)
magnetic Field30
No magnetic field - vulnerable to solar radiation
geology60
Some geological activity provides slow nutrient cycling
Organic Chemistry80
Core organic elements (CHNO) present
rotation30
Very slow rotation - days and nights each last several Earth days, bringing severe temperature swings

Physical Properties

Mass
0.69x Earth (4.13e+24 kg)
Radius
0.88x Earth (5,635 km)
This planet: 0.88× Earth radiusEarth: 1× (baseline)
Surface Gravity
0.88x Earth (8.7 m/s²)
Surface Temperature
253 K (-20 °C / -4 °F)
Rotation Period
146.4 hours/day (slower than Earth)
This planet: 146 h/dayEarth: 24 h/day

Elemental Composition

How TerraForge built this world

TRAPPIST-1 e, from the NASA Exoplanet Archive (found 2017). Measured: 0.692 Earth masses, 0.0293 AU, a 2566 K M-type star. Composition inferred from a measured bulk density of 0.89x Earth's, which is rock and iron, with a day locked to its 6.1-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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