HD 118203 c
HD 118203 c is a cold gas giant orbiting HD 118203 in the constellation Ursa Major. It lies about 301 light-years from Earth and was discovered in 2024 using the radial velocity method.
Is HD 118203 c in the Habitable Zone?
HD 118203 c orbits beyond the outer edge of the habitable zone of HD 118203. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 118203: 1.515–3.573 AU (conservative: 1.919–3.388 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 118203 c — one full orbit around HD 118203 — lasts 5,103.0 Earth days, longer than Jupiter's 12-year orbit. It orbits at an average distance of 6.280 AU. Its orbit is mildly elliptical (eccentricity 0.26).
How Was HD 118203 c Discovered?
HD 118203 c was discovered in 2024 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 HD 118203 c?
HD 118203 c is 300.9 light-years (92.3 parsecs) from Earth. Light arriving here tonight left the planet around the year 1726. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 5,295,840 years to make the journey.
The Host Star: HD 118203
HD 118203
- Surface temperature
- 5,742 K (Sun: 5,772 K)
- Mass
- 1.27 M☉
- Radius
- 2.04 R☉
- Age
- 4.7 billion years (Sun: 4.6)
The HD 118203 Planetary System
HD 118203 c is one of 2 known planets in the HD 118203 system. Its siblings:
- HD 118203 b (Hot Jupiter)
HD 118203 c — Complete Data
| Mass | 3,747.20 Earth masses (11.790 Jupiter masses) |
|---|---|
| Orbital period | 5,103.00 days |
| Orbital distance | 6.280 AU |
| Eccentricity | 0.260 |
| Distance from Earth | 300.9 light-years (92.3 parsecs) |
| Constellation | Ursa Major |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2024 |
Data: NASA Exoplanet Archive, last updated 2025-05-27. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 118203 c
Is HD 118203 c habitable?
No — HD 118203 c orbits outside the habitable zone of HD 118203 and is likely too cold for liquid water on its surface.
How far away is HD 118203 c?
HD 118203 c is about 301 light-years from Earth in the constellation Ursa Major. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 5,295,840 years to get there.
How long is a year on HD 118203 c?
One orbit around HD 118203 takes 5,103.0 Earth days.
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