Gliese 48 b
Gliese 48 b is a super-Earth orbiting the M3.5 V star Gliese 48 in the constellation Cassiopeia. It lies about 27 light-years from Earth and was discovered in 2026 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 Gliese 48 b in the Habitable Zone?
Gliese 48 b orbits inside the conservative habitable zone of Gliese 48 — 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 Gliese 48: 0.135–0.352 AU (conservative: 0.171–0.333 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on Gliese 48 b
The equilibrium temperature of Gliese 48 b is about 271 K (-2 °C) — in a range broadly comparable to Earth, whose equilibrium temperature is 255 K. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 0.89 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on Gliese 48 b — one full orbit around Gliese 48 — lasts 39.6 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.175 AU — closer to its star than Mercury is to the Sun.
How Was Gliese 48 b Discovered?
Gliese 48 b was discovered in 2026 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 Gliese 48 b?
Gliese 48 b is 26.9 light-years (8.2 parsecs) from Earth. Light arriving here tonight left the planet around the year 2000. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 473,440 years to make the journey.
The Host Star: Gliese 48
Gliese 48
- Spectral type
- M3.5 V
- Surface temperature
- 3,450 K (Sun: 5,772 K)
- Mass
- 0.47 M☉
- Radius
- 0.46 R☉
- Luminosity
- 0.0273 L☉
Planetary System
Gliese 48 b is the only planet known to orbit Gliese 48 so far.
Gliese 48 b — Complete Data
| Mass (best estimate) | 8.11 Earth masses |
|---|---|
| Orbital period | 39.63 days |
| Orbital distance | 0.175 AU |
| Equilibrium temperature | 271 K (-2 °C) |
| Stellar irradiation | 0.89× Earth |
| Distance from Earth | 26.9 light-years (8.2 parsecs) |
| Constellation | Cassiopeia |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2026 |
Data: NASA Exoplanet Archive, last updated 2026-07-30. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Gliese 48 b
Is Gliese 48 b habitable?
Gliese 48 b orbits within the habitable zone of Gliese 48, 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 Gliese 48 b?
Gliese 48 b is about 27 light-years from Earth in the constellation Cassiopeia. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 473,440 years to get there.
How long is a year on Gliese 48 b?
One orbit around Gliese 48 takes 39.6 Earth days.
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