HAT-P-11 c
HAT-P-11 c is a cold gas giant orbiting HAT-P-11 in the constellation Cygnus. It lies about 123 light-years from Earth and was discovered in 2018 using the radial velocity method.
Is HAT-P-11 c in the Habitable Zone?
The position of HAT-P-11 c relative to the habitable zone of HAT-P-11 cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on HAT-P-11 c — one full orbit around HAT-P-11 — lasts 3,361.0 Earth days, longer than an Earth year. It orbits at an average distance of 4.100 AU. Its orbit is highly elliptical (eccentricity 0.65), swinging dramatically closer to and farther from its star.
How Was HAT-P-11 c Discovered?
HAT-P-11 c was discovered in 2018 using the radial velocity method, with observations from W. M. Keck 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 HAT-P-11 c?
HAT-P-11 c is 123.2 light-years (37.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1903. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,168,320 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. HAT-P-11 c scores 0.09, ranking #4,534 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HAT-P-11
HAT-P-11
- Mass
- 0.81 M☉
The HAT-P-11 Planetary System
HAT-P-11 c is one of 2 known planets in the HAT-P-11 system. Its siblings:
- HAT-P-11 b (Neptune-like)
HAT-P-11 c — Complete Data
| Mass | 851.78 Earth masses (2.680 Jupiter masses) |
|---|---|
| Orbital period | 3,361.00 days |
| Orbital distance | 4.100 AU |
| Eccentricity | 0.652 |
| Earth Similarity Index | 0.09 |
| Distance from Earth | 123.2 light-years (37.8 parsecs) |
| Constellation | Cygnus |
| Discovery method | Radial Velocity |
| Discovery facility | W. M. Keck Observatory |
| Discovery year | 2018 |
Data: NASA Exoplanet Archive, last updated 2025-02-24. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HAT-P-11 c
Is HAT-P-11 c habitable?
HAT-P-11 c is not known to orbit within the habitable zone of HAT-P-11, and as a cold gas giant it is an unlikely candidate for life as we know it.
How far away is HAT-P-11 c?
HAT-P-11 c is about 123 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,168,320 years to get there.
How long is a year on HAT-P-11 c?
One orbit around HAT-P-11 takes 3,361.0 Earth days.
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