GJ 1148 c
GJ 1148 c is a cold gas giant orbiting GJ 1148 in the constellation Ursa Major. It lies about 36 light-years from Earth and was discovered in 2017 using the radial velocity method.
Is GJ 1148 c in the Habitable Zone?
GJ 1148 c orbits beyond the outer edge of the habitable zone of GJ 1148. At that distance, any surface water would almost certainly be frozen.
Habitable zone of GJ 1148: 0.095–0.250 AU (conservative: 0.121–0.237 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Orbit and Year Length
A year on GJ 1148 c — one full orbit around GJ 1148 — lasts 532.6 Earth days, longer than an Earth year. It orbits at an average distance of 0.912 AU — comparable to the inner Solar System. Its orbit is highly elliptical (eccentricity 0.34), swinging dramatically closer to and farther from its star.
How Was GJ 1148 c Discovered?
GJ 1148 c was discovered in 2017 using the radial velocity method, with observations from Calar Alto 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 GJ 1148 c?
GJ 1148 c is 35.9 light-years (11.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1991. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 631,840 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 1148 c scores 0.11, ranking #4,392 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: GJ 1148
GJ 1148
- Surface temperature
- 3,287 K (Sun: 5,772 K)
- Mass
- 0.34 M☉
- Radius
- 0.36 R☉
- Luminosity
- 0.0135 L☉
The GJ 1148 Planetary System
GJ 1148 c is one of 2 known planets in the GJ 1148 system. Its siblings:
- GJ 1148 b (Cold Gas Giant)
GJ 1148 c — Complete Data
| Mass (best estimate) | 68.06 Earth masses |
|---|---|
| Orbital period | 532.58 days |
| Orbital distance | 0.912 AU |
| Eccentricity | 0.342 |
| Earth Similarity Index | 0.11 |
| Distance from Earth | 35.9 light-years (11.0 parsecs) |
| Constellation | Ursa Major |
| Discovery method | Radial Velocity |
| Discovery facility | Calar Alto Observatory |
| Discovery year | 2017 |
Data: NASA Exoplanet Archive, last updated 2017-10-16. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About GJ 1148 c
Is GJ 1148 c habitable?
No — GJ 1148 c orbits outside the habitable zone of GJ 1148 and is likely too cold for liquid water on its surface.
How far away is GJ 1148 c?
GJ 1148 c is about 36 light-years from Earth in the constellation Ursa Major. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 631,840 years to get there.
How long is a year on GJ 1148 c?
One orbit around GJ 1148 takes 532.6 Earth days.
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