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SELECTED WORLDLHS 1140 b
LHS 1140 · M4.5 V host star · cool red dwarf · main sequence
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.
The marker above the bar is a typical temperature for this star’s class. The line below is Earth’s Sun.
LHS 1140 is class M4.5 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.
Most plausible case. A heavy world: 1.73 Earth radii and 5.6 Earth masses, gravity 1.87 g, measured. It receives only about 43% of Earth’s light around a 0.22-solar-radius star that spans about 1.2°. A 2024 JWST study reported a possible nitrogen-rich atmosphere and raised a water-world interpretation. If that holds, the ground may be a global ocean under ice, with a thinner ice patch under the star. If the atmosphere hint fades, it is a dense rocky or watery super-Earth under a cold red sun. The surface has not been seen.
Dry case. Bare high-gravity rock and dust, frost where water failed to pool. The high density still allows a large rock fraction, so a dry heavy planet remains possible.
Thick-air case. The JWST hint, if real, is a thick high-mean-molecular-weight sky, not a puff of hydrogen. Cloud or haze could hide the ocean or the rock.
Walking. About 87% heavier than Earth, measured. You would feel it immediately. LHS 1140 c is a small disk, under a fifth of the Moon’s width. The light is dim and red, under half of Earth’s energy. The star is magnitude 14, 49 light-years away.
Based on: Dittmann et al. 2017; Cadieux et al. 2024 JWST; Teff 3096 K, R 0.22 Rsun, S 0.43, Rp 1.73, Mp 5.6, a 0.095 AU
LHS 1140 b circles LHS 1140. Also shown: LHS 1140 c, 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.
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.
