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Entering orbit…
Habitability
76/ 100
Habitable

Reading TRAPPIST-1 c’s atmosphere

Dominant elements: O, Si, Fe, N, H, CThis is what a telescope would measure while TRAPPIST-1 c 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 c 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.

TRAPPIST-1 c

Earth LikeHabitable40 light years awayFound 2016

TRAPPIST-1 c, from the NASA Exoplanet Archive (found 2016). Measured: 1.31 Earth masses, 0.0158 AU, a 2566 K M-type star. Composition inferred from a measured bulk density of 0.98x Earth's, which is rock and iron, with a day locked to its 2.4-day year, as anything orbiting this close would be.

Host star

TRAPPIST-1

Type
M-type (Red Dwarf)
Spectral type
M8.0 V
Temperature
2,566 K
Radius
0.119 ☉
Mass
0.0898 ☉
Known planets
7, including this one
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.

Earth Like

Life DetectedMagnetic FieldModerate Activity
Why is this a Earth Like?Your planet has a balanced composition with all CHNOPS elements, proper mass (1.3x Earth), and sits in the habitable zone at 0.02 AU.
Earth-like planets have the perfect combination of composition, temperature, mass, and magnetic field to potentially support complex life as we know it.
Classification Criteria:
✓ All CHNOPS elements present (C, H, N, O, P, S)✓ Mass: 1.3x Earth (0.5-2.0x range)✓ Temperature: 347K (250-320K range)✓ Magnetic field present✓ Distance: 0.02 AU (habitable zone)
Further reading
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.Exoplanets: Diamond Worlds, Super Earths, Pulsar PlanetsMichael Summers & James TrefilThe strange end of the catalogue — carbon worlds, molten rock, planets orbiting dead stars.
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Habitability ScoreHabitable
76
Contributing Factors
temperature70
Challenging but potentially habitable temperature
atmosphere100
Nitrogen-oxygen atmosphere - breathable and protective
water50
Limited water content
magnetic Field100
Magnetic field provides radiation protection
geology90
Active geology recycles nutrients and drives carbon cycle
Organic Chemistry80
Core organic elements (CHNO) present
rotation65
Slow rotation - significant day/night temperature variations, but life can adapt

Physical Properties

Mass
1.31x Earth (7.82e+24 kg)
Radius
1.09x Earth (6,971 km)
This planet: 1.09× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.09x Earth (10.7 m/s²)
Surface Temperature
347 K (74 °C / 164 °F)
Rotation Period
58.1 hours/day (slower than Earth)
This planet: 58 h/dayEarth: 24 h/day

Orbital Environment

Star Type
M-type (Red Dwarf)
Distance from Star
0.02 AU (2.36 million km)
Orbital Period
1 day
Time Dilation
Clocks run 8.9 seconds per year slower than deep space — about 12 minutes over a lifetime

Atmosphere

Nitrogen-oxygen atmosphere with trace CO₂, water vapor, and argon

Elemental Composition

O - Oxygen
31.1%
Si - Silicon
24.0%
Fe - Iron
12.1%

Surface Characteristics

Rocky surface with continents, oceans, and active plate tectonics. Diverse biomes if life present.

Habitability

✓ Conditions suitable for life detectedThis planet exhibits the necessary conditions to support biological processes, including stable temperatures, liquid water, and protective magnetic fields.
A binary star system's orrery: two suns close together, a red dashed dead-zone boundary, and a debris trail left by a destroyed world

New: Binary Star Systems 🌀

A system can now orbit two suns. Add a companion star when you build one — close, medium, or wide — and the physics decides what survives: a shared center of mass carves out a dead zone where gravity from both stars tears a world apart, leaving it as debris, and every surviving planet's orbit goes elliptical, moving fastest at closest approach and slowest out at aphelion. Push the separation to wide and the dead zone opens tens of AU across, wide enough to gut a system that would have been stable around one star alone. Stand on a world that made it through and you'll watch two suns cross the sky together.

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