GJ 740 b
GJ 740 b is a super-Earth orbiting the M1.0 V star GJ 740 in the constellation Serpens. It lies about 36 light-years from Earth and was discovered in 2021 using the radial velocity method.
Is GJ 740 b in the Habitable Zone?
GJ 740 b orbits inside the inner edge of the habitable zone of GJ 740. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of GJ 740: 0.203–0.515 AU (conservative: 0.257–0.489 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on GJ 740 b
The equilibrium temperature of GJ 740 b is about 829 K (556 °C) — hot enough to melt many metals. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 79.00 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on GJ 740 b — one full orbit around GJ 740 — lasts 2.38 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.029 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.24).
How Was GJ 740 b Discovered?
GJ 740 b was discovered in 2021 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 740 b?
GJ 740 b is 36.2 light-years (11.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1990. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 637,120 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 740 b scores 0.30, ranking #1,538 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: GJ 740
GJ 740
- Spectral type
- M1.0 V
- Surface temperature
- 3,913 K (Sun: 5,772 K)
- Mass
- 0.58 M☉
- Radius
- 0.56 R☉
- Luminosity
- 0.0622 L☉
Planetary System
GJ 740 b is the only planet known to orbit GJ 740 so far.
GJ 740 b — Complete Data
| Mass (best estimate) | 2.96 Earth masses |
|---|---|
| Orbital period | 2.38 days |
| Orbital distance | 0.029 AU |
| Eccentricity | 0.240 |
| Equilibrium temperature | 829 K (556 °C) |
| Stellar irradiation | 79.00× Earth |
| Earth Similarity Index | 0.30 |
| Distance from Earth | 36.2 light-years (11.1 parsecs) |
| Constellation | Serpens |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2021 |
Data: NASA Exoplanet Archive, last updated 2021-03-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About GJ 740 b
Is GJ 740 b habitable?
No — GJ 740 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is GJ 740 b?
GJ 740 b is about 36 light-years from Earth in the constellation Serpens. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 637,120 years to get there.
How long is a year on GJ 740 b?
One orbit around GJ 740 takes 2.4 Earth days — short enough that 154 of its years would fit into one Earth year.
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