HAT-P-17 c
HAT-P-17 c is a cold gas giant orbiting HAT-P-17 in the constellation Cygnus. It lies about 301 light-years from Earth and was discovered in 2012 using the radial velocity method.
Is HAT-P-17 c in the Habitable Zone?
HAT-P-17 c orbits beyond the outer edge of the habitable zone of HAT-P-17. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HAT-P-17: 0.555–1.329 AU (conservative: 0.703–1.260 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 HAT-P-17 c — one full orbit around HAT-P-17 — lasts 5,584.0 Earth days, longer than Jupiter's 12-year orbit. It orbits at an average distance of 5.600 AU. Its orbit is highly elliptical (eccentricity 0.39), swinging dramatically closer to and farther from its star.
How Was HAT-P-17 c Discovered?
HAT-P-17 c was discovered in 2012 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-17 c?
HAT-P-17 c is 301.3 light-years (92.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1725. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 5,302,880 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-17 c scores 0.09, ranking #4,548 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HAT-P-17
HAT-P-17
- Surface temperature
- 5,246 K (Sun: 5,772 K)
- Mass
- 0.99 M☉
- Radius
- 0.87 R☉
The HAT-P-17 Planetary System
HAT-P-17 c is one of 2 known planets in the HAT-P-17 system. Its siblings:
- HAT-P-17 b (Cold Gas Giant)
HAT-P-17 c — Complete Data
| Mass (best estimate) | 1,080.60 Earth masses |
|---|---|
| Orbital period | 5,584.00 days |
| Orbital distance | 5.600 AU |
| Eccentricity | 0.390 |
| Earth Similarity Index | 0.09 |
| Distance from Earth | 301.3 light-years (92.4 parsecs) |
| Constellation | Cygnus |
| Discovery method | Radial Velocity |
| Discovery facility | W. M. Keck Observatory |
| Discovery year | 2012 |
Data: NASA Exoplanet Archive, last updated 2014-05-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HAT-P-17 c
Is HAT-P-17 c habitable?
No — HAT-P-17 c orbits outside the habitable zone of HAT-P-17 and is likely too cold for liquid water on its surface.
How far away is HAT-P-17 c?
HAT-P-17 c is about 301 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 5,302,880 years to get there.
How long is a year on HAT-P-17 c?
One orbit around HAT-P-17 takes 5,584.0 Earth days.
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