Host star — TRAPPIST-1
- Spectral type
- M8.0 V
- Temperature
- 2,566 K
- Radius
- 0.12 R☉
- Mass
- 0.09 M☉
- Luminosity
- 0.001 L☉
- Distance
- 12.4 pc (40.5 ly)
Red dwarf — the most common type of star. Cool and small.
Very cool — a faint red dwarf.
TRAPPIST-1 e
Orbits TRAPPIST-1 · 40.5 light-years from Earth
RockyTransit2017ESI 96 · Very Earth-like
Radius
0.92×
Earth
Mass
0.7×
Earth
Year
6d
Temp
250 K
-23°C
Gravity
0.8×
Earth
Distance
40.5
ly
Could life exist here?
AI analysisTRAPPIST-1 e orbits a dim red dwarf just 40.5 light-years away, making it one of the nearest potentially habitable worlds known. The planet is nearly Earth's size—92 percent of Earth's radius—with a density of 4.9 g/cm³ suggesting a rocky composition similar to our own planet. Its equilibrium temperature of 250 Kelvin sits well below freezing, but because the star is so cool and dim, the planet likely receives moderate stellar flux; if it harbors a thick atmosphere, greenhouse warming could push its surface into the temperate range needed for liquid water. The planet orbits every 6.1 days at just 0.029 AU from its host star, raising questions about tidal locking, though its low eccentricity (0.0051) suggests a stable orbit. With a habitability score of 96 out of 100, TRAPPIST-1 e ranks among the most promising exoplanet candidates, though confirmation of atmospheric composition and surface conditions remains years away. Its discovery by the transit method in 2017 opened the door to studying a compact system of seven rocky worlds, and TRAPPIST-1 e may soon be within reach of the James Webb Space Telescope.
What it would be like
TRAPPIST-1 e is a rocky world, potentially similar in composition to Earth or Mars — a solid surface you could, in theory, stand on.
Surface gravity is about 0.8g — noticeably lighter what you're used to on Earth.
At -23°C, this world is cold — similar to Earth's polar regions or the surface of Mars. Water would likely be frozen, but subsurface liquid isn't ruled out.
A year here is only 6.1 Earth days. Seasons, if they exist, change in a matter of hours.
Earth comparison
Logarithmic bars so Jupiter-class planets fit the same scale as Earth-size worlds.
Radius0.92R⊕
1/25×Earth = 125×
Mass0.69M⊕
1/10000×Earth = 110000×
Surface gravity0.82g
1/100×Earth = 1100×
Equilibrium temp250 K(-23°C)
0 KEarth 255 K2500 K
Side-by-side with Earth
Temperature in context
Liquid N₂Mars avgEarth eq.Earth sfc.Boiling H₂OVenus
Discovery & orbit
- Method
- Transit
- Year
- 2017
- Facility
- Multiple Observatories
- Semi-major axis
- 0.0293 AU
- Period
- 6.10 days
- Eccentricity
- 0.0051
- Density
- 4.90 g/cm³
Detected by measuring the tiny dip in starlight as the planet crosses in front of its star.
Nearly circular orbit.
Rocky composition likely. Earth is 5.51 g/cm³.
Discovered via · Transit
Tiny dip in starlight as the planet crosses in front of its star
A transit photometer watches a star nonstop and measures its brightness to ~0.01%. When a planet passes between us and the star, the star dims briefly — the deeper the dip, the bigger the planet. This is how Kepler and TESS found most known exoplanets.
- Overall share
- ~75% of all confirmed worlds
- Best for
- Earth-to-Neptune-sized planets on short orbits
Orbital Animation
TRAPPIST-1TRAPPIST-1 eOrbitHabitable zone
Drag to rotate · scroll to zoomSemi-major axis: 0.029 AUEccentricity: 0.0051Period: 6.1 days
Hertzsprung–Russell Diagram
Where this host star sits among … exoplanet host stars. The main sequence band runs diagonally — giants and supergiants sit above, white dwarfs below.
OBAFGKMCurrent star
How far is 40.5 light-years?
- A light beam leaving Earth right now would arrive in 40.5 years.
- At Voyager 1's speed (17 km/s), the trip would take approximately 714,952 years.
- A radio signal sent today would arrive in 40.5 years — and the reply wouldn't come back for twice that.
Earth Similarity Index
96/1000 — Nothing like Earth100 — Identical to Earth
ESI combines radius similarity and equilibrium temperature similarity. Earth = 100. Mars ≈ 73. Venus ≈ 44. This score reflects two physical parameters only — not atmosphere, water, or magnetic field.