HD 211810 b
HD 211810 b is a cold gas giant orbiting the G5 star HD 211810 in the constellation Cepheus. It lies about 211 light-years from Earth and was discovered in 2018 using the radial velocity method.
Is HD 211810 b in the Habitable Zone?
HD 211810 b orbits beyond the outer edge of the habitable zone of HD 211810. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 211810: 0.820–1.938 AU (conservative: 1.038–1.837 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Orbit and Year Length
A year on HD 211810 b — one full orbit around HD 211810 — lasts 1,558.0 Earth days, longer than an Earth year. It orbits at an average distance of 2.656 AU. Its orbit is highly elliptical (eccentricity 0.68), swinging dramatically closer to and farther from its star.
How Was HD 211810 b Discovered?
HD 211810 b was discovered in 2018 using the radial velocity method, with observations from W. M. Keck 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 211810 b?
HD 211810 b is 210.8 light-years (64.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1816. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,710,080 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 211810 b scores 0.24, ranking #3,265 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 211810
HD 211810
- Spectral type
- G5
- Surface temperature
- 5,652 K (Sun: 5,772 K)
- Mass
- 1.03 M☉
- Radius
- 1.13 R☉
- Luminosity
- 1.1749 L☉
Planetary System
HD 211810 b is the only planet known to orbit HD 211810 so far.
HD 211810 b — Complete Data
| Mass (best estimate) | 212.95 Earth masses |
|---|---|
| Orbital period | 1,558.00 days |
| Orbital distance | 2.656 AU |
| Eccentricity | 0.680 |
| Earth Similarity Index | 0.24 |
| Distance from Earth | 210.8 light-years (64.6 parsecs) |
| Constellation | Cepheus |
| Discovery method | Radial Velocity |
| Discovery facility | W. M. Keck Observatory |
| Discovery year | 2018 |
Data: NASA Exoplanet Archive, last updated 2018-09-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 211810 b
Is HD 211810 b habitable?
No — HD 211810 b orbits outside the habitable zone of HD 211810 and is likely too cold for liquid water on its surface.
How far away is HD 211810 b?
HD 211810 b is about 211 light-years from Earth in the constellation Cepheus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,710,080 years to get there.
How long is a year on HD 211810 b?
One orbit around HD 211810 takes 1,558.0 Earth days.
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