HIP 5158 b
HIP 5158 b is a cold gas giant orbiting HIP 5158 in the constellation Cetus. It lies about 168 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 HIP 5158 b in the Habitable Zone?
HIP 5158 b orbits inside the conservative habitable zone of HIP 5158 — 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 HIP 5158: 0.414–1.009 AU (conservative: 0.525–0.957 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 HIP 5158 b — one full orbit around HIP 5158 — lasts 345.7 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.890 AU — comparable to the inner Solar System. Its orbit is highly elliptical (eccentricity 0.52), swinging dramatically closer to and farther from its star.
How Was HIP 5158 b Discovered?
HIP 5158 b was discovered in 2009 using the radial velocity method, with observations from La Silla 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 HIP 5158 b?
HIP 5158 b is 168.3 light-years (51.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1858. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,962,080 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. HIP 5158 b scores 0.21, ranking #3,832 of 5,565 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HIP 5158
HIP 5158
- Surface temperature
- 4,813 K (Sun: 5,772 K)
- Mass
- 0.78 M☉
- Radius
- 0.75 R☉
- Luminosity
- 0.2749 L☉
The HIP 5158 Planetary System
HIP 5158 b is one of 2 known planets in the HIP 5158 system. Its siblings:
HIP 5158 b — Complete Data
| Mass (best estimate) | 451.00 Earth masses |
|---|---|
| Orbital period | 345.72 days |
| Orbital distance | 0.890 AU |
| Eccentricity | 0.520 |
| Earth Similarity Index | 0.21 |
| Distance from Earth | 168.3 light-years (51.6 parsecs) |
| Constellation | Cetus |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 2009 |
Data: NASA Exoplanet Archive, last updated 2019-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HIP 5158 b
Is HIP 5158 b habitable?
HIP 5158 b orbits within the habitable zone of HIP 5158, 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 HIP 5158 b?
HIP 5158 b is about 168 light-years from Earth in the constellation Cetus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,962,080 years to get there.
How long is a year on HIP 5158 b?
One orbit around HIP 5158 takes 345.7 Earth days.
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