HR 810 b
HR 810 b is a cold gas giant orbiting HR 810 in the constellation Horologium. It lies about 57 light-years from Earth and was discovered in 1999 using the radial velocity method.
Is HR 810 b in the Habitable Zone?
HR 810 b orbits inside the inner edge of the habitable zone of HR 810. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HR 810: 0.943–2.203 AU (conservative: 1.195–2.088 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 HR 810 b — one full orbit around HR 810 — lasts 302.8 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.920 AU — comparable to the inner Solar System. Its orbit is mildly elliptical (eccentricity 0.14).
How Was HR 810 b Discovered?
HR 810 b was discovered in 1999 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 HR 810 b?
HR 810 b is 56.5 light-years (17.3 parsecs) from Earth. Light arriving here tonight left the planet around the year 1970. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 994,400 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. HR 810 b scores 0.34, ranking #850 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HR 810
HR 810
- Surface temperature
- 6,167 K (Sun: 5,772 K)
- Mass
- 1.34 M☉
- Radius
- 1.13 R☉
Planetary System
HR 810 b is the only planet known to orbit HR 810 so far.
HR 810 b — Complete Data
| Mass (best estimate) | 721.47 Earth masses |
|---|---|
| Orbital period | 302.80 days |
| Orbital distance | 0.920 AU |
| Eccentricity | 0.140 |
| Earth Similarity Index | 0.34 |
| Distance from Earth | 56.5 light-years (17.3 parsecs) |
| Constellation | Horologium |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 1999 |
Data: NASA Exoplanet Archive, last updated 2018-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HR 810 b
Is HR 810 b habitable?
No — HR 810 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HR 810 b?
HR 810 b is about 57 light-years from Earth in the constellation Horologium. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 994,400 years to get there.
How long is a year on HR 810 b?
One orbit around HR 810 takes 302.8 Earth days.
Explore HR 810 b in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
