GJ 1148 b
GJ 1148 b 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 2010 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 1148 b in the Habitable Zone?
GJ 1148 b orbits inside the conservative habitable zone of GJ 1148 — 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 1148: 0.095–0.250 AU (conservative: 0.121–0.237 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Orbit and Year Length
A year on GJ 1148 b — one full orbit around GJ 1148 — lasts 41.4 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.166 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.38), swinging dramatically closer to and farther from its star.
How Was GJ 1148 b Discovered?
GJ 1148 b was discovered in 2010 using the radial velocity method, with observations from W. M. Keck 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 b?
GJ 1148 b 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 b scores 0.36, ranking #671 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 b is one of 2 known planets in the GJ 1148 system. Its siblings:
- GJ 1148 c (Cold Gas Giant)
GJ 1148 b — Complete Data
| Mass (best estimate) | 96.70 Earth masses |
|---|---|
| Orbital period | 41.38 days |
| Orbital distance | 0.166 AU |
| Eccentricity | 0.380 |
| Earth Similarity Index | 0.36 |
| Distance from Earth | 35.9 light-years (11.0 parsecs) |
| Constellation | Ursa Major |
| Discovery method | Radial Velocity |
| Discovery facility | W. M. Keck Observatory |
| Discovery year | 2010 |
Data: NASA Exoplanet Archive, last updated 2017-10-16. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About GJ 1148 b
Is GJ 1148 b habitable?
GJ 1148 b orbits within the habitable zone of GJ 1148, 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 1148 b?
GJ 1148 b 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 b?
One orbit around GJ 1148 takes 41.4 Earth days.
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