GJ 1002 c
GJ 1002 c is a terrestrial planet orbiting the M5.5 V star GJ 1002 in the constellation Cetus. It lies about 16 light-years from Earth and was discovered in 2022 using the radial velocity method. It orbits within the habitable zone of its star — the region where liquid water could exist on a planet's surface.
Is GJ 1002 c in the Habitable Zone?
GJ 1002 c orbits inside the conservative habitable zone of GJ 1002 — the region where a rocky planet could sustain liquid water on its surface. This makes it one of the most interesting known exoplanets in the search for life.
Habitable zone of GJ 1002: 0.031–0.082 AU (conservative: 0.039–0.078 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on GJ 1002 c
The equilibrium temperature of GJ 1002 c is about 182 K (-91 °C) — well below freezing. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 0.26 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on GJ 1002 c — one full orbit around GJ 1002 — lasts 21.2 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.074 AU — closer to its star than Mercury is to the Sun.
How Was GJ 1002 c Discovered?
GJ 1002 c was discovered in 2022 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 1002 c?
GJ 1002 c is 15.8 light-years (4.8 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 278,080 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. GJ 1002 c scores 0.58, ranking #153 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: GJ 1002
GJ 1002
- Spectral type
- M5.5 V
- Surface temperature
- 3,024 K (Sun: 5,772 K)
- Mass
- 0.12 M☉
- Radius
- 0.14 R☉
- Luminosity
- 0.0014 L☉
The GJ 1002 Planetary System
GJ 1002 c is one of 2 known planets in the GJ 1002 system. Its siblings:
- GJ 1002 b (Terrestrial)
GJ 1002 c — Complete Data
| Mass (best estimate) | 1.36 Earth masses |
|---|---|
| Orbital period | 21.20 days |
| Orbital distance | 0.074 AU |
| Equilibrium temperature | 182 K (-91 °C) |
| Stellar irradiation | 0.26× Earth |
| Earth Similarity Index | 0.58 |
| Distance from Earth | 15.8 light-years (4.8 parsecs) |
| Constellation | Cetus |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2022-12-17. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About GJ 1002 c
Is GJ 1002 c habitable?
GJ 1002 c orbits within the habitable zone of GJ 1002, the region where liquid water could exist on a planet's surface. It sits in the conservative habitable zone — the most promising region for habitability. Whether it is actually habitable depends on its atmosphere and composition, which remain unknown.
How far away is GJ 1002 c?
GJ 1002 c is about 16 light-years from Earth in the constellation Cetus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 278,080 years to get there.
How long is a year on GJ 1002 c?
One orbit around GJ 1002 takes 21.2 Earth days — short enough that 17 of its years would fit into one Earth year.
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