LHS 3154 b
LHS 3154 b is a Neptune-like planet orbiting the M6.5 star LHS 3154 in the constellation Hercules. It lies about 51 light-years from Earth and was discovered in 2023 using the radial velocity method.
Is LHS 3154 b in the Habitable Zone?
LHS 3154 b orbits inside the inner edge of the habitable zone of LHS 3154. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of LHS 3154: 0.036–0.096 AU (conservative: 0.045–0.091 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Orbit and Year Length
A year on LHS 3154 b — one full orbit around LHS 3154 — lasts 3.72 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.023 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.08).
How Was LHS 3154 b Discovered?
LHS 3154 b was discovered in 2023 using the radial velocity method, with observations from McDonald Observatory.
The radial velocity method measures the subtle wobble of a star caused by the gravitational pull of an orbiting planet, visible as periodic shifts in the star's light spectrum. The size of the wobble reveals the planet's minimum mass.
How Far Away Is LHS 3154 b?
LHS 3154 b is 51.4 light-years (15.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1975. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 904,640 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 3154 b scores 0.42, ranking #402 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: LHS 3154
LHS 3154
- Spectral type
- M6.5
- Surface temperature
- 2,861 K (Sun: 5,772 K)
- Mass
- 0.11 M☉
- Radius
- 0.14 R☉
- Luminosity
- 0.0019 L☉
- Age
- 5.0 billion years (Sun: 4.6)
Planetary System
LHS 3154 b is the only planet known to orbit LHS 3154 so far.
LHS 3154 b — Complete Data
| Mass (best estimate) | 13.15 Earth masses |
|---|---|
| Orbital period | 3.72 days |
| Orbital distance | 0.023 AU |
| Eccentricity | 0.076 |
| Earth Similarity Index | 0.42 |
| Distance from Earth | 51.4 light-years (15.8 parsecs) |
| Constellation | Hercules |
| Discovery method | Radial Velocity |
| Discovery facility | McDonald Observatory |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-12-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About LHS 3154 b
Is LHS 3154 b habitable?
No — LHS 3154 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is LHS 3154 b?
LHS 3154 b is about 51 light-years from Earth in the constellation Hercules. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 904,640 years to get there.
How long is a year on LHS 3154 b?
One orbit around LHS 3154 takes 3.7 Earth days — short enough that 98 of its years would fit into one Earth year.
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