PH1 b
PH1 b is a cold gas giant orbiting the F star PH1 in the constellation Cygnus. It lies about 3,370 light-years from Earth and was discovered in 2012 using the transit method.
How Big Is PH1 b?
PH1 b has a radius of 6.18 times that of Earth, or 0.55 times the radius of Jupiter. Its mass is 169 times that of Earth.
Is PH1 b in the Habitable Zone?
PH1 b orbits inside the inner edge of the habitable zone of PH1. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of PH1: 1.540–3.580 AU (conservative: 1.951–3.395 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on PH1 b
The equilibrium temperature of PH1 b is about 481 K (208 °C) — hotter than anywhere on Earth. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C.
Orbit and Year Length
A year on PH1 b — one full orbit around PH1 — lasts 138.3 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.652 AU — comparable to the inner Solar System. Its orbit is mildly elliptical (eccentricity 0.07).
How Was PH1 b Discovered?
PH1 b was discovered in 2012 using the transit method, with observations from Kepler.
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 PH1 b?
PH1 b is 3,369.7 light-years (1,033.2 parsecs) from Earth. Light arriving here tonight left the planet about 3,370 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 59,306,720 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. PH1 b scores 0.22, ranking #3,622 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: PH1
PH1 b is a circumbinary planet — it orbits around two stars at once, like Tatooine in Star Wars.
PH1
- Spectral type
- F
- Surface temperature
- 6,407 K (Sun: 5,772 K)
- Mass
- 1.53 M☉
- Radius
- 1.73 R☉
- Age
- 2.0 billion years (Sun: 4.6)
Planetary System
PH1 b is the only planet known to orbit PH1 so far.
PH1 b — Complete Data
| Radius | 6.180 Earth radii (0.551 Jupiter radii) |
|---|---|
| Mass | 169.00 Earth masses (0.531 Jupiter masses) |
| Orbital period | 138.32 days |
| Orbital distance | 0.652 AU |
| Eccentricity | 0.070 |
| Equilibrium temperature | 481 K (208 °C) |
| Earth Similarity Index | 0.22 |
| Distance from Earth | 3,369.7 light-years (1,033.2 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2012 |
Data: NASA Exoplanet Archive, last updated 2014-05-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About PH1 b
Is PH1 b habitable?
No — PH1 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is PH1 b?
PH1 b is about 3,370 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 59,306,720 years to get there.
How big is PH1 b compared to Earth?
PH1 b has 6.18 times the radius of Earth and about 169 times its mass.
How long is a year on PH1 b?
One orbit around PH1 takes 138.3 Earth days.
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