gam Cep b
gam Cep b is a cold gas giant orbiting gam Cep in the constellation Cepheus. It lies about 46 light-years from Earth and was discovered in 2003 using the radial velocity method.
Is gam Cep b in the Habitable Zone?
The position of gam Cep b relative to the habitable zone of gam Cep cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on gam Cep b — one full orbit around gam Cep — lasts 904.0 Earth days, longer than an Earth year. It orbits at an average distance of 1.978 AU. Its orbit is mildly elliptical (eccentricity 0.07).
How Was gam Cep b Discovered?
gam Cep b was discovered in 2003 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 gam Cep b?
gam Cep b is 46.0 light-years (14.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1980. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 809,600 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. gam Cep b scores 0.31, ranking #1,156 of 5,565 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: gam Cep
gam Cep b belongs to a system of 2 stars; it orbits gam Cep.
gam Cep
- Mass
- 1.26 M☉
Planetary System
gam Cep b is the only planet known to orbit gam Cep so far.
gam Cep b — Complete Data
| Mass (best estimate) | 514.88 Earth masses |
|---|---|
| Orbital period | 904.00 days |
| Orbital distance | 1.978 AU |
| Eccentricity | 0.070 |
| Earth Similarity Index | 0.31 |
| Distance from Earth | 46.0 light-years (14.1 parsecs) |
| Constellation | Cepheus |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2003 |
Data: NASA Exoplanet Archive, last updated 2026-09-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About gam Cep b
Is gam Cep b habitable?
gam Cep b is not known to orbit within the habitable zone of gam Cep, and as a cold gas giant it is an unlikely candidate for life as we know it.
How far away is gam Cep b?
gam Cep b is about 46 light-years from Earth in the constellation Cepheus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 809,600 years to get there.
How long is a year on gam Cep b?
One orbit around gam Cep takes 904.0 Earth days.
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