LHS 1678 d
LHS 1678 d is a terrestrial planet orbiting the M2.0 V star LHS 1678 in the constellation Caelum. It lies about 65 light-years from Earth and was discovered in 2024 using the transit method.
How Big Is LHS 1678 d?
LHS 1678 d has a radius of 0.98 times that of Earth.
Is LHS 1678 d in the Habitable Zone?
LHS 1678 d orbits inside the inner edge of the habitable zone of LHS 1678. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of LHS 1678: 0.099–0.256 AU (conservative: 0.125–0.242 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Temperature on LHS 1678 d
LHS 1678 d receives 9.10 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on LHS 1678 d — one full orbit around LHS 1678 — lasts 4.97 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.040 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.036).
How Was LHS 1678 d Discovered?
LHS 1678 d was discovered in 2024 using the transit method, with observations from Transiting Exoplanet Survey Satellite (TESS).
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 1678 d?
LHS 1678 d is 64.8 light-years (19.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1962. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,140,480 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 1678 d scores 0.43, ranking #384 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: LHS 1678
LHS 1678 d belongs to a system of 2 stars; it orbits LHS 1678.
LHS 1678
- Spectral type
- M2.0 V
- Surface temperature
- 3,490 K (Sun: 5,772 K)
- Mass
- 0.35 M☉
- Radius
- 0.33 R☉
- Luminosity
- 0.0145 L☉
- Age
- 7.0 billion years (Sun: 4.6)
The LHS 1678 Planetary System
LHS 1678 d is one of 3 known planets in the LHS 1678 system. Its siblings:
- LHS 1678 b (Terrestrial)
- LHS 1678 c (Terrestrial)
LHS 1678 d — Complete Data
| Radius | 0.981 Earth radii (0.088 Jupiter radii) |
|---|---|
| Orbital period | 4.97 days |
| Orbital distance | 0.040 AU |
| Eccentricity | 0.036 |
| Stellar irradiation | 9.10× Earth |
| Earth Similarity Index | 0.43 |
| Distance from Earth | 64.8 light-years (19.9 parsecs) |
| Constellation | Caelum |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2024 |
Data: NASA Exoplanet Archive, last updated 2024-03-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About LHS 1678 d
Is LHS 1678 d habitable?
No — LHS 1678 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is LHS 1678 d?
LHS 1678 d is about 65 light-years from Earth in the constellation Caelum. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,140,480 years to get there.
How big is LHS 1678 d compared to Earth?
LHS 1678 d has 0.98 times the radius of Earth.
How long is a year on LHS 1678 d?
One orbit around LHS 1678 takes 5.0 Earth days — short enough that 74 of its years would fit into one Earth year.
Explore LHS 1678 d in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
