Barnard d
Barnard d is a terrestrial planet orbiting the M3.5-4 V star Barnard's star in the constellation Ophiuchus. It lies about 6 light-years from Earth and was discovered in 2025 using the radial velocity method.
Is Barnard d in the Habitable Zone?
Barnard d orbits inside the inner edge of the habitable zone of Barnard's star. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Barnard's star: 0.049–0.129 AU (conservative: 0.062–0.122 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on Barnard d
The equilibrium temperature of Barnard d is about 483 K (210 °C) — hotter than anywhere on Earth. 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 Barnard d — one full orbit around Barnard's star — lasts 2.34 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.019 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.040).
How Was Barnard d Discovered?
Barnard d was discovered in 2025 using the radial velocity method, with observations from Gemini 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 Barnard d?
Barnard d is 6.0 light-years (1.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 2020. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 105,600 years to make the journey.
The Host Star: Barnard's star
Barnard's star
- Spectral type
- M3.5-4 V
- Surface temperature
- 3,195 K (Sun: 5,772 K)
- Mass
- 0.16 M☉
- Radius
- 0.19 R☉
- Luminosity
- 0.0036 L☉
The Barnard's star Planetary System
Barnard d is one of 4 known planets in the Barnard's star system. Its siblings:
Barnard d — Complete Data
| Mass (best estimate) | 0.26 Earth masses |
|---|---|
| Orbital period | 2.34 days |
| Orbital distance | 0.019 AU |
| Eccentricity | 0.040 |
| Equilibrium temperature | 483 K (210 °C) |
| Distance from Earth | 6.0 light-years (1.8 parsecs) |
| Constellation | Ophiuchus |
| Discovery method | Radial Velocity |
| Discovery facility | Gemini Observatory |
| Discovery year | 2025 |
Data: NASA Exoplanet Archive, last updated 2025-03-10. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Barnard d
Is Barnard d habitable?
No — Barnard d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Barnard d?
Barnard d is about 6 light-years from Earth in the constellation Ophiuchus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 105,600 years to get there.
How long is a year on Barnard d?
One orbit around Barnard's star takes 2.3 Earth days — short enough that 156 of its years would fit into one Earth year.
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