GJ 414 A b
GJ 414 A b is a mini-Neptune orbiting the K7 V star GJ 414 A in the constellation Ursa Major. It lies about 39 light-years from Earth and was discovered in 2021 using the radial velocity method.
How Big Is GJ 414 A b?
GJ 414 A b has a radius of 2.63 times that of Earth. Its mass is 7.6 times that of Earth.
Is GJ 414 A b in the Habitable Zone?
GJ 414 A b orbits inside the inner edge of the habitable zone of GJ 414 A. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of GJ 414 A: 0.279–0.702 AU (conservative: 0.353–0.666 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on GJ 414 A b
The equilibrium temperature of GJ 414 A b is about 309 K (35 °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.
Orbit and Year Length
A year on GJ 414 A b — one full orbit around GJ 414 A — lasts 50.8 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.232 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.45), swinging dramatically closer to and farther from its star.
How Was GJ 414 A b Discovered?
GJ 414 A b was discovered in 2021 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 414 A b?
GJ 414 A b is 38.8 light-years (11.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1988. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 682,880 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 414 A b scores 0.56, ranking #175 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: GJ 414 A
GJ 414 A b belongs to a system of 2 stars; it orbits GJ 414 A.
GJ 414 A
- Spectral type
- K7 V
- Surface temperature
- 4,120 K (Sun: 5,772 K)
- Mass
- 0.65 M☉
- Radius
- 0.68 R☉
- Luminosity
- 0.1190 L☉
- Age
- 12.4 billion years (Sun: 4.6)
The GJ 414 A Planetary System
GJ 414 A b is one of 2 known planets in the GJ 414 A system. Its siblings:
- GJ 414 A c (Cold Gas Giant)
GJ 414 A b — Complete Data
| Radius | 2.630 Earth radii (0.235 Jupiter radii) |
|---|---|
| Mass (best estimate) | 7.60 Earth masses |
| Orbital period | 50.80 days |
| Orbital distance | 0.232 AU |
| Eccentricity | 0.450 |
| Equilibrium temperature | 309 K (35 °C) |
| Earth Similarity Index | 0.56 |
| Distance from Earth | 38.8 light-years (11.9 parsecs) |
| Constellation | Ursa Major |
| Discovery method | Radial Velocity |
| Discovery facility | W. M. Keck Observatory |
| Discovery year | 2021 |
Data: NASA Exoplanet Archive, last updated 2021-03-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About GJ 414 A b
Is GJ 414 A b habitable?
No — GJ 414 A b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is GJ 414 A b?
GJ 414 A b is about 39 light-years from Earth in the constellation Ursa Major. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 682,880 years to get there.
How big is GJ 414 A b compared to Earth?
GJ 414 A b has 2.63 times the radius of Earth and about 7.6 times its mass.
How long is a year on GJ 414 A b?
One orbit around GJ 414 A takes 50.8 Earth days.
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