HD 216770 b
HD 216770 b is a cold gas giant orbiting HD 216770 in the constellation Piscis Austrinus. It lies about 120 light-years from Earth and was discovered in 2003 using the radial velocity method.
Is HD 216770 b in the Habitable Zone?
HD 216770 b orbits inside the inner edge of the habitable zone of HD 216770. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 216770: 0.623–1.484 AU (conservative: 0.789–1.407 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 216770 b — one full orbit around HD 216770 — lasts 118.5 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.460 AU — comparable to the inner Solar System. Its orbit is highly elliptical (eccentricity 0.37), swinging dramatically closer to and farther from its star.
How Was HD 216770 b Discovered?
HD 216770 b was discovered in 2003 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 216770 b?
HD 216770 b is 119.6 light-years (36.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1907. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,104,960 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 216770 b scores 0.25, ranking #3,039 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 216770
HD 216770
- Surface temperature
- 5,399 K (Sun: 5,772 K)
- Mass
- 0.74 M☉
- Radius
- 0.93 R☉
Planetary System
HD 216770 b is the only planet known to orbit HD 216770 so far.
HD 216770 b — Complete Data
| Mass (best estimate) | 181.16 Earth masses |
|---|---|
| Orbital period | 118.45 days |
| Orbital distance | 0.460 AU |
| Eccentricity | 0.370 |
| Earth Similarity Index | 0.25 |
| Distance from Earth | 119.6 light-years (36.7 parsecs) |
| Constellation | Piscis Austrinus |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 2003 |
Data: NASA Exoplanet Archive, last updated 2018-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 216770 b
Is HD 216770 b habitable?
No — HD 216770 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 216770 b?
HD 216770 b is about 120 light-years from Earth in the constellation Piscis Austrinus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,104,960 years to get there.
How long is a year on HD 216770 b?
One orbit around HD 216770 takes 118.5 Earth days.
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