WASP-59 b
WASP-59 b is a hot Jupiter orbiting the K5 V star WASP-59 in the constellation Pegasus. It lies about 378 light-years from Earth and was discovered in 2012 using the transit method.
How Big Is WASP-59 b?
WASP-59 b has a radius of 8.69 times that of Earth, or 0.78 times the radius of Jupiter. Its mass is 274 times that of Earth, giving it a density of 2.40 g/cm³ — between that of rocky and gaseous planets.
Is WASP-59 b in the Habitable Zone?
WASP-59 b orbits inside the inner edge of the habitable zone of WASP-59. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of WASP-59: 0.316–0.775 AU (conservative: 0.400–0.735 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on WASP-59 b
The equilibrium temperature of WASP-59 b is about 670 K (397 °C) — hot enough to melt many metals. 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 WASP-59 b — one full orbit around WASP-59 — lasts 7.92 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.070 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.10).
How Was WASP-59 b Discovered?
WASP-59 b was discovered in 2012 using the transit method, with observations from SuperWASP.
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 WASP-59 b?
WASP-59 b is 378.1 light-years (115.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1648. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 6,654,560 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. WASP-59 b scores 0.13, ranking #4,289 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: WASP-59
WASP-59
- Spectral type
- K5 V
- Surface temperature
- 4,650 K (Sun: 5,772 K)
- Mass
- 0.72 M☉
- Radius
- 0.61 R☉
- Age
- 0.5 billion years (Sun: 4.6)
Planetary System
WASP-59 b is the only planet known to orbit WASP-59 so far.
WASP-59 b — Complete Data
| Radius | 8.687 Earth radii (0.775 Jupiter radii) |
|---|---|
| Mass | 274.28 Earth masses (0.863 Jupiter masses) |
| Density | 2.40 g/cm³ (Earth: 5.51) |
| Orbital period | 7.92 days |
| Orbital distance | 0.070 AU |
| Eccentricity | 0.100 |
| Equilibrium temperature | 670 K (397 °C) |
| Earth Similarity Index | 0.13 |
| Distance from Earth | 378.1 light-years (115.9 parsecs) |
| Constellation | Pegasus |
| Discovery method | Transit |
| Discovery facility | SuperWASP |
| Discovery year | 2012 |
Data: NASA Exoplanet Archive, last updated 2014-05-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About WASP-59 b
Is WASP-59 b habitable?
No — WASP-59 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is WASP-59 b?
WASP-59 b is about 378 light-years from Earth in the constellation Pegasus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,654,560 years to get there.
How big is WASP-59 b compared to Earth?
WASP-59 b has 8.69 times the radius of Earth and about 274 times its mass.
How long is a year on WASP-59 b?
One orbit around WASP-59 takes 7.9 Earth days — short enough that 46 of its years would fit into one Earth year.
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