Expedition 01 · about 40.5 light-years
Chart the seven worlds of TRAPPIST-1
Select a world, run a spectral scan to reveal what the James Webb Space Telescope has measured, and build your Captain's Log across the system's resonant chain. Orbits are drawn to scale.
Target locked
TRAPPIST-1e
TRAPPIST-1 planets at a glance
TRAPPIST-1 is an M8 V ultracool dwarf about 40.5 light-years (12.43 pc) from the Sun, with 0.119 times the Sun's radius and a surface temperature of about 2,566 K. Its seven planets are all roughly Earth-sized and all orbit closer to their star than Mercury does to the Sun. Equilibrium temperature assumes no atmosphere and no reflected light, so it is not a surface temperature.
| Planet | Radius (Earth = 1) | Mass (Earth = 1) | Period (days) | Equilibrium temp | Sunlight (Earth = 1) |
|---|---|---|---|---|---|
| TRAPPIST-1b | 1.116 | 1.374 | 1.511 | 398 K (125 °C) | 4.15 |
JWSTDayside 490 ± 17 K with no detectable night-side heat: best fit is a dark, airless rock. Thick CO₂ atmospheres strongly disfavoured. Source for TRAPPIST-1b JWST notes: Gillon et al. 2026, Nature Astronomy (opens in a new tab) | |||||
| TRAPPIST-1c | 1.097 | 1.308 | 2.422 | 340 K (67 °C) | 2.21 |
JWSTDayside 369 ± 23 K: either airless or a thin, oxygen-rich atmosphere with little greenhouse warming. No Venus-like CO₂ blanket. Source for TRAPPIST-1c JWST notes: Gillon et al. 2026, Nature Astronomy (opens in a new tab) | |||||
| TRAPPIST-1d | 0.788 | 0.388 | 4.049 | 286 K (13 °C) | 1.12 |
JWSTFlat transmission spectrum: clear hydrogen atmospheres ruled out; any air is very thin or hidden by high clouds. Source for TRAPPIST-1d JWST notes: Piaulet-Ghorayeb et al. 2025 (arXiv) (opens in a new tab) | |||||
| TRAPPIST-1e | 0.920 | 0.692 | 6.101 | 250 K (−23 °C) | 0.65 |
JWSTHydrogen-rich air disfavoured; a nitrogen atmosphere with traces of CO₂ or methane, or bare rock, both still allowed. Starspots complicate the data. Source for TRAPPIST-1e JWST notes: JWST-TST DREAMS 2025 (arXiv) (opens in a new tab) | |||||
| TRAPPIST-1f | 1.045 | 1.039 | 9.208 | 218 K (−55 °C) | 0.37 |
JWSTFirst spectra (Aug 2026): hydrogen-helium atmospheres above about 20 mbar ruled out; flares seen in every visit. Source for TRAPPIST-1f JWST notes: Lim et al. 2026 (arXiv) (opens in a new tab) | |||||
| TRAPPIST-1g | 1.129 | 1.321 | 12.352 | 197 K (−76 °C) | 0.25 |
JWSTNo published JWST atmosphere constraints as of Oct 2026. Source for TRAPPIST-1g JWST notes: NASA Exoplanet Archive: TRAPPIST-1 overview (opens in a new tab) | |||||
| TRAPPIST-1h | 0.755 | 0.326 | 18.773 | 172 K (−101 °C) | 0.14 |
JWSTNo published JWST atmosphere constraints as of Oct 2026. Source for TRAPPIST-1h JWST notes: NASA Exoplanet Archive: TRAPPIST-1 overview (opens in a new tab) | |||||
Sources: NASA Exoplanet Archive: TRAPPIST-1 overview (composite parameters, queried 2026-10-10) and Agol et al. 2021, Planetary Science Journal 2:1. Planet colours on the map are illustrative: no TRAPPIST-1 planet has a measured colour.