HD 6718 b
The parameters of this planet are disputed or ambiguous in the scientific literature.
HD 6718 b is a cold gas giant orbiting the G5 V star HD 6718 in the constellation Cetus. It lies about 168 light-years from Earth and was discovered in 2009 using the radial velocity method.
Is HD 6718 b in the Habitable Zone?
HD 6718 b orbits beyond the outer edge of the habitable zone of HD 6718. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 6718: 0.758–1.788 AU (conservative: 0.961–1.696 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 ›
Orbit and Year Length
A year on HD 6718 b — one full orbit around HD 6718 — lasts 2,476.0 Earth days, longer than an Earth year. It orbits at an average distance of 3.530 AU. Its orbit is mildly elliptical (eccentricity 0.06).
How Was HD 6718 b Discovered?
HD 6718 b was discovered in 2009 using the radial velocity method, with observations from La Silla 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 HD 6718 b?
HD 6718 b is 167.5 light-years (51.3 parsecs) from Earth. Light arriving here tonight left the planet around the year 1859. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,948,000 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. HD 6718 b scores 0.15, ranking #4,202 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 6718
HD 6718
- Spectral type
- G5 V
- Surface temperature
- 5,746 K (Sun: 5,772 K)
- Mass
- 0.96 M☉
- Radius
- 1.02 R☉
Planetary System
HD 6718 b is the only planet known to orbit HD 6718 so far.
HD 6718 b — Complete Data
| Mass | 762.79 Earth masses (2.400 Jupiter masses) |
|---|---|
| Orbital period | 2,476.00 days |
| Orbital distance | 3.530 AU |
| Eccentricity | 0.060 |
| Earth Similarity Index | 0.15 |
| Distance from Earth | 167.5 light-years (51.3 parsecs) |
| Constellation | Cetus |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 2009 |
Data: NASA Exoplanet Archive, last updated 2026-06-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 6718 b
Is HD 6718 b habitable?
No — HD 6718 b orbits outside the habitable zone of HD 6718 and is likely too cold for liquid water on its surface.
How far away is HD 6718 b?
HD 6718 b is about 168 light-years from Earth in the constellation Cetus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,948,000 years to get there.
How long is a year on HD 6718 b?
One orbit around HD 6718 takes 2,476.0 Earth days.
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