75 Cet b
75 Cet b is a cold gas giant orbiting the G3 III star 75 Cet in the constellation Cetus. It lies about 271 light-years from Earth and was discovered in 2012 using the radial velocity method.
Is 75 Cet b in the Habitable Zone?
75 Cet b orbits inside the inner edge of the habitable zone of 75 Cet. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of 75 Cet: 5.688–13.860 AU (conservative: 7.204–13.140 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 75 Cet b — one full orbit around 75 Cet — lasts 696.6 Earth days, longer than an Earth year. It orbits at an average distance of 1.912 AU. Its orbit is mildly elliptical (eccentricity 0.09).
How Was 75 Cet b Discovered?
75 Cet b was discovered in 2012 using the radial velocity method, with observations from Okayama Astrophysical 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 75 Cet b?
75 Cet b is 270.6 light-years (83.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1756. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 4,762,560 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. 75 Cet b scores 0.14, ranking #4,267 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: 75 Cet
75 Cet b belongs to a system of 2 stars; it orbits 75 Cet.
75 Cet
- Spectral type
- G3 III
- Surface temperature
- 4,809 K (Sun: 5,772 K)
- Mass
- 1.92 M☉
- Radius
- 10.38 R☉
- Luminosity
- 51.8203 L☉
The 75 Cet Planetary System
75 Cet b is one of 2 known planets in the 75 Cet system. Its siblings:
- 75 Cet c (Cold Gas Giant)
75 Cet b — Complete Data
| Mass (best estimate) | 787.90 Earth masses |
|---|---|
| Orbital period | 696.62 days |
| Orbital distance | 1.912 AU |
| Eccentricity | 0.093 |
| Earth Similarity Index | 0.14 |
| Distance from Earth | 270.6 light-years (83.0 parsecs) |
| Constellation | Cetus |
| Discovery method | Radial Velocity |
| Discovery facility | Okayama Astrophysical Observatory |
| Discovery year | 2012 |
Data: NASA Exoplanet Archive, last updated 2023-09-19. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About 75 Cet b
Is 75 Cet b habitable?
No — 75 Cet b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is 75 Cet b?
75 Cet b is about 271 light-years from Earth in the constellation Cetus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 4,762,560 years to get there.
How long is a year on 75 Cet b?
One orbit around 75 Cet takes 696.6 Earth days.
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