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TRAPPIST-1 f

TRAPPIST-1 · M8.0 V host star · cool red dwarf · main sequence

[ TRAPPIST_1_F.IMG ]
VIEW 1 · ON THE SURFACE
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Artist’s impression of TRAPPIST-1 f: VIEW 1 · ON THE SURFACE
VIEW 1 · ON THE SURFACE · Artist’s impression. No surface has been seen.
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40.5 light-years from Earth
[ FACTS.DAT ]
Right ascension / declination346.626° / -5.043°J2000 / ICRS
Gravity0.95 × Earthderived from measured mass + radius
Year9.21 days
From its star0.0385 AUabout 5.8 million km
Stars in the system1 star7 known planets in system
Stars this world orbits1 starOrbits TRAPPIST-1
Day and nightLikely synchronous spinProbably spins once per orbit, keeping one hemisphere in permanent day and the other in permanent night. Heuristic: likely at ≤0.25 AU, uncertain to 0.50 AU, probably not beyond; rotation is not directly measured.
[ TEMP.EST ]MODELLED, NOT MEASURED
Host star≈2,600 Ktypical M8.0 V · 0.12 Sun radii
No atmosphere202 K · -71°C30% reflective · heat shared
Earth-like air235 K · -38°CBaseline plus 33°C

Star temperature and orbital distance set incoming energy, but stellar size is also required. This calculation uses a typical radius for the listed spectral type, 30% reflectivity and even heat redistribution. It is not a ground-temperature forecast: air, clouds, oceans and surface reflectivity could move the result by tens to hundreds of degrees. A likely synchronous spin also means the permanent day and night sides would not share one ground temperature.

[ STARLIGHT.SPC ]VISIBLE LIGHT ONLY

The marker above the bar is a typical temperature for this star’s class. The line below is Earth’s Sun.

red-orange

TRAPPIST-1 is class M8.0 V. Its visible daylight would be dim and strongly red-orange; most of its energy is infrared.

Representative lit-side geometry only. On a locked world, the star’s real elevation would depend on where you stand.

[ GROUND.TXT ]STILL INFERENCE

Most plausible case. Farther out and colder: about 37% of Earth’s light. Size and mass are both near Earth’s (1.05 radii, 1.04 masses), so the weight is close to Earth’s and measured. The star spans about 1.7°. Ice is more plausible across the day side than on planet e. Open water wants a greenhouse. The night side is a cold trap.

Dry case. Cold rock and frost, not a hot dune field. A thin sky leaves most of the ground near or below freezing.

Thick-air case. A CO₂-rich atmosphere is the interesting thick-air case here: it could warm the ground and also cover it in cloud. A hydrogen envelope is not supported by the density.

Walking. About Earth’s weight, measured, a little lighter at 0.95 g. Planet g would look about 1.3 times the Moon’s width, and planet e about as wide as the Moon. The star is still a large red disk, smaller than it looks from d or e.

Based on: Agol et al. 2021; S 0.37, Rp 1.05, Mp 1.04, a 0.038 AU

[ ORBIT.SYS ]7 KNOWN · ALL SHOWN
100% · Above 30°

TRAPPIST-1 f circles TRAPPIST-1. Also shown: TRAPPIST-1 b, TRAPPIST-1 c, TRAPPIST-1 d, TRAPPIST-1 e, TRAPPIST-1 g, TRAPPIST-1 h, each on its NASA-catalogued orbit. Use Higher and Lower to move your viewpoint above, through and below the orbital plane, and − / + to zoom. Orbit shapes and spacing are schematic.

[ SOURCES.TXT ]

Positions, distances, and system parameters come from the NASA Exoplanet Archive composite table, queried 25 Sep 2026. GJ 273 b uses the parallax in that row, 12.4 light-years. The 45 worlds follow Bohl, Lawrence, Lowry, and Kaltenegger.