GJ 229 A c
The parameters of this planet are disputed or ambiguous in the scientific literature.
GJ 229 A c is a super-Earth orbiting GJ 229 in the constellation Lepus. It lies about 19 light-years from Earth and was discovered in 2020 using the radial velocity method.
Is GJ 229 A c in the Habitable Zone?
The position of GJ 229 A c relative to the habitable zone of GJ 229 cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on GJ 229 A c — one full orbit around GJ 229 — lasts 121.9 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.384 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.37), swinging dramatically closer to and farther from its star.
How Was GJ 229 A c Discovered?
GJ 229 A c was discovered in 2020 using the radial velocity method, with observations from Multiple Facilities.
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 229 A c?
GJ 229 A c is 18.8 light-years (5.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 2008. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 330,880 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 229 A c scores 0.56, ranking #178 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: GJ 229
GJ 229 A c belongs to a system of 3 stars; it orbits GJ 229.
GJ 229
- Mass
- 0.51 M☉
The GJ 229 Planetary System
GJ 229 A c is one of 2 known planets in the GJ 229 system. Its siblings:
- GJ 229 b (Neptune-like)
GJ 229 A c — Complete Data
| Mass (best estimate) | 8.58 Earth masses |
|---|---|
| Orbital period | 121.93 days |
| Orbital distance | 0.384 AU |
| Eccentricity | 0.366 |
| Earth Similarity Index | 0.56 |
| Distance from Earth | 18.8 light-years (5.8 parsecs) |
| Constellation | Lepus |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Facilities |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2023-06-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About GJ 229 A c
Is GJ 229 A c habitable?
GJ 229 A c is not known to orbit within the habitable zone of GJ 229, and as a super-Earth it is an unlikely candidate for life as we know it.
How far away is GJ 229 A c?
GJ 229 A c is about 19 light-years from Earth in the constellation Lepus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 330,880 years to get there.
How long is a year on GJ 229 A c?
One orbit around GJ 229 takes 121.9 Earth days.
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