GJ 876 b
GJ 876 b is a cold gas giant orbiting GJ 876 in the constellation Aquarius. It lies about 15 light-years from Earth and was discovered in 1998 using the radial velocity method.
Is GJ 876 b in the Habitable Zone?
The position of GJ 876 b relative to the habitable zone of GJ 876 cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on GJ 876 b — one full orbit around GJ 876 — lasts 61.1 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.208 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.032).
How Was GJ 876 b Discovered?
GJ 876 b was discovered in 1998 using the radial velocity method, with observations from Multiple Observatories.
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 GJ 876 b?
GJ 876 b is 15.2 light-years (4.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 2011. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 267,520 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. GJ 876 b scores 0.28, ranking #2,398 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: GJ 876
GJ 876
- Mass
- 0.32 M☉
- Radius
- 0.30 R☉
- Luminosity
- 0.0124 L☉
- Age
- 1.0 billion years (Sun: 4.6)
The GJ 876 Planetary System
GJ 876 b is one of 4 known planets in the GJ 876 system. Its siblings:
GJ 876 b — Complete Data
| Mass | 723.22 Earth masses (2.276 Jupiter masses) |
|---|---|
| Orbital period | 61.12 days |
| Orbital distance | 0.208 AU |
| Eccentricity | 0.032 |
| Earth Similarity Index | 0.28 |
| Distance from Earth | 15.2 light-years (4.7 parsecs) |
| Constellation | Aquarius |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 1998 |
Data: NASA Exoplanet Archive, last updated 2014-08-27. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About GJ 876 b
Is GJ 876 b habitable?
GJ 876 b is not known to orbit within the habitable zone of GJ 876, and as a cold gas giant it is an unlikely candidate for life as we know it.
How far away is GJ 876 b?
GJ 876 b is about 15 light-years from Earth in the constellation Aquarius. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 267,520 years to get there.
How long is a year on GJ 876 b?
One orbit around GJ 876 takes 61.1 Earth days.
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