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Plate No. 3,420 — in order of discoveryEntered 2017-02-22

TRAPPIST-1 e

A temperate terrestrial world orbiting TRAPPIST-1, a M8.0 V star, 40.5 ly from Earth. One of 7 charted worlds in its system.

Enter the system →Find it in the night sky →
0.01 AUTRAPPIST-1 e
7 worldstemperate zone1s = 1s

Orbit shapes and relative timing are true — worlds sweep faster near their star, as Kepler demands. Spacing is drawn to true scale when the system allows; wide systems open compressed so inner and outer worlds share the page. Dashed orbits are derived from period alone.

The measures

Earth

1.0 R⊕

TRAPPIST-1 e

0.92 R⊕

frozenEarth 255 K · e 250 Kstar-hot

Life outlook

Conceivable

52/ 100
Warmth
99 · weight 40%

~250 K equilibrium vs Earth's 255 K

Size
97 · weight 30%

0.92 R⊕ vs Earth's 1.0 — larger worlds trend gaseous

Star
4 · weight 20%

2566 K dwarf vs the Sun's 5772 K — flares and tidal lock

Orbit
100 · weight 10%

e = 0.0051 vs Earth's 0.017 — swings mean climate whiplash

A strict Earth-similarity index, not a detection: every factor peaks at Earth's own value and they multiply, so one hostile factor sinks the score — only a true Earth twin would reach 100. Equilibrium temperature ignores atmospheres, which can warm a cold world into comfort, or turn a Venus into a furnace.

The world

Class
Terrestrial
Radius
0.92 R⊕
Mass
0.692 M⊕
Density
4.9 g/cm³
Equilibrium temperature
250 K
Starlight received
0.65× Earth

The orbit

Period
6.101 days
Semi-major axis
0.0293 AU
Eccentricity
0.0051

The star

Host
TRAPPIST-1
Spectral type
M8.0 V
Temperature
2,566 K
Radius
0.12 R☉
Mass
0.09 M☉

The system

Distance
40.5 ly · 12.4 pc
Known planets
7
Stars
1
Coordinates
RA 346.63° · Dec -5.04°

The observation

Star brightness
V 17 · telescope
Atmospheric spectra
6 transmission · 0 emission
Stellar age
7.6 Gyr

The record

Method
Transit
Facility
Multiple Observatories
Discovery
2017
Parameters published
—
Discovery paperGillon et al. 2017