HAT-P-17 b
HAT-P-17 b 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 transit method.
How Big Is HAT-P-17 b?
HAT-P-17 b has a radius of 11.77 times that of Earth, or 1.05 times the radius of Jupiter. Its mass is 184 times that of Earth.
Is HAT-P-17 b in the Habitable Zone?
The position of HAT-P-17 b relative to the habitable zone of HAT-P-17 cannot be precisely determined from the available orbital data.
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 b — one full orbit around HAT-P-17 — lasts 10.3 Earth days, shorter than Mercury's 88-day year. Its orbit is highly elliptical (eccentricity 0.35), swinging dramatically closer to and farther from its star.
How Was HAT-P-17 b Discovered?
HAT-P-17 b was discovered in 2012 using the transit method, with observations from HATNet.
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is HAT-P-17 b?
HAT-P-17 b 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 b scores 0.09, ranking #4,518 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 b is one of 2 known planets in the HAT-P-17 system. Its siblings:
- HAT-P-17 c (Cold Gas Giant)
HAT-P-17 b — Complete Data
| Radius | 11.769 Earth radii (1.050 Jupiter radii) |
|---|---|
| Mass | 184.34 Earth masses (0.580 Jupiter masses) |
| Orbital period | 10.34 days |
| Eccentricity | 0.350 |
| Earth Similarity Index | 0.09 |
| Distance from Earth | 301.3 light-years (92.4 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | HATNet |
| Discovery year | 2012 |
Data: NASA Exoplanet Archive, last updated 2018-04-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HAT-P-17 b
Is HAT-P-17 b habitable?
HAT-P-17 b is not known to orbit within the habitable zone of HAT-P-17, and as a cold gas giant it is an unlikely candidate for life as we know it.
How far away is HAT-P-17 b?
HAT-P-17 b 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 big is HAT-P-17 b compared to Earth?
HAT-P-17 b has 11.77 times the radius of Earth and about 184 times its mass.
How long is a year on HAT-P-17 b?
One orbit around HAT-P-17 takes 10.3 Earth days — short enough that 35 of its years would fit into one Earth year.
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