LHS 1140 c
LHS 1140 c is a super-Earth orbiting the M4.5 V star LHS 1140 in the constellation Cetus. It lies about 49 light-years from Earth and was discovered in 2018 using the transit method.
How Big Is LHS 1140 c?
LHS 1140 c has a radius of 1.27 times that of Earth. Its mass is 1.9 times that of Earth, giving it a density of 5.10 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is LHS 1140 c in the Habitable Zone?
LHS 1140 c orbits inside the inner edge of the habitable zone of LHS 1140. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of LHS 1140: 0.051–0.134 AU (conservative: 0.064–0.127 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on LHS 1140 c
The equilibrium temperature of LHS 1140 c is about 422 K (149 °C) — hotter than anywhere on Earth. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 5.30 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on LHS 1140 c — one full orbit around LHS 1140 — lasts 3.78 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.027 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.05).
How Was LHS 1140 c Discovered?
LHS 1140 c was discovered in 2018 using the transit method, with observations from Multiple Observatories.
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is LHS 1140 c?
LHS 1140 c is 48.9 light-years (15.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1978. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 860,640 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. LHS 1140 c scores 0.51, ranking #241 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: LHS 1140
LHS 1140
- Spectral type
- M4.5 V
- Surface temperature
- 3,096 K (Sun: 5,772 K)
- Mass
- 0.18 M☉
- Radius
- 0.22 R☉
- Luminosity
- 0.0038 L☉
- Age
- 5.0 billion years (Sun: 4.6)
The LHS 1140 Planetary System
LHS 1140 c is one of 2 known planets in the LHS 1140 system. Its siblings:
- LHS 1140 b (Super Earth)
LHS 1140 c — Complete Data
| Radius | 1.272 Earth radii (0.113 Jupiter radii) |
|---|---|
| Mass | 1.91 Earth masses (0.006 Jupiter masses) |
| Density | 5.10 g/cm³ (Earth: 5.51) |
| Orbital period | 3.78 days |
| Orbital distance | 0.027 AU |
| Eccentricity | 0.050 |
| Equilibrium temperature | 422 K (149 °C) |
| Stellar irradiation | 5.30× Earth |
| Earth Similarity Index | 0.51 |
| Distance from Earth | 48.9 light-years (15.0 parsecs) |
| Constellation | Cetus |
| Discovery method | Transit |
| Discovery facility | Multiple Observatories |
| Discovery year | 2018 |
Data: NASA Exoplanet Archive, last updated 2024-03-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About LHS 1140 c
Is LHS 1140 c habitable?
No — LHS 1140 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is LHS 1140 c?
LHS 1140 c is about 49 light-years from Earth in the constellation Cetus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 860,640 years to get there.
How big is LHS 1140 c compared to Earth?
LHS 1140 c has 1.27 times the radius of Earth and about 1.9 times its mass.
How long is a year on LHS 1140 c?
One orbit around LHS 1140 takes 3.8 Earth days — short enough that 97 of its years would fit into one Earth year.
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