HD 38801 b
HD 38801 b is a cold gas giant orbiting HD 38801 in the constellation Orion. It lies about 298 light-years from Earth and was discovered in 2009 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 HD 38801 b in the Habitable Zone?
HD 38801 b orbits within the optimistic habitable zone of HD 38801 — the broader region where liquid water might be possible under favorable atmospheric conditions.
Habitable zone of HD 38801: 1.333–3.183 AU (conservative: 1.689–3.018 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 HD 38801 b — one full orbit around HD 38801 — lasts 685.3 Earth days, longer than an Earth year. It orbits at an average distance of 1.623 AU. Its orbit is nearly circular (eccentricity 0.017).
How Was HD 38801 b Discovered?
HD 38801 b was discovered in 2009 using the radial velocity method, with observations from Subaru Telescope.
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 HD 38801 b?
HD 38801 b is 298.2 light-years (91.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1728. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 5,248,320 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. HD 38801 b scores 0.37, ranking #636 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 38801
HD 38801
- Surface temperature
- 5,338 K (Sun: 5,772 K)
- Mass
- 1.21 M☉
- Radius
- 2.03 R☉
- Age
- 6.1 billion years (Sun: 4.6)
Planetary System
HD 38801 b is the only planet known to orbit HD 38801 so far.
HD 38801 b — Complete Data
| Mass (best estimate) | 3,082.32 Earth masses |
|---|---|
| Orbital period | 685.25 days |
| Orbital distance | 1.623 AU |
| Eccentricity | 0.017 |
| Earth Similarity Index | 0.37 |
| Distance from Earth | 298.2 light-years (91.4 parsecs) |
| Constellation | Orion |
| Discovery method | Radial Velocity |
| Discovery facility | Subaru Telescope |
| Discovery year | 2009 |
Data: NASA Exoplanet Archive, last updated 2019-06-24. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 38801 b
Is HD 38801 b habitable?
HD 38801 b orbits within the habitable zone of HD 38801, the region where liquid water could exist on a planet's surface. Whether it is actually habitable depends on its atmosphere and composition, which remain unknown.
How far away is HD 38801 b?
HD 38801 b is about 298 light-years from Earth in the constellation Orion. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 5,248,320 years to get there.
How long is a year on HD 38801 b?
One orbit around HD 38801 takes 685.3 Earth days.
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