WASP-102 b
WASP-102 b is a hot Jupiter orbiting WASP-102 in the constellation Pegasus. It lies about 1,747 light-years from Earth and was discovered in 2025 using the transit method.
How Big Is WASP-102 b?
WASP-102 b has a radius of 14.91 times that of Earth, or 1.33 times the radius of Jupiter. Its mass is 198 times that of Earth, giving it a density of 0.32 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is WASP-102 b in the Habitable Zone?
WASP-102 b orbits inside the inner edge of the habitable zone of WASP-102. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of WASP-102: 1.095–2.566 AU (conservative: 1.387–2.433 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on WASP-102 b
The equilibrium temperature of WASP-102 b is about 1,671 K (1,398 °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. It receives 1,293 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on WASP-102 b — one full orbit around WASP-102 — lasts 2.71 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.041 AU — closer to its star than Mercury is to the Sun.
How Was WASP-102 b Discovered?
WASP-102 b was discovered in 2025 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-102 b?
WASP-102 b is 1,747.2 light-years (535.7 parsecs) from Earth. Light arriving here tonight left the planet about 1,747 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 30,750,720 years to make the journey.
The Host Star: WASP-102
WASP-102
- Surface temperature
- 5,990 K (Sun: 5,772 K)
- Mass
- 1.08 M☉
- Radius
- 1.38 R☉
- Age
- 0.7 billion years (Sun: 4.6)
Planetary System
WASP-102 b is the only planet known to orbit WASP-102 so far.
WASP-102 b — Complete Data
| Radius | 14.908 Earth radii (1.330 Jupiter radii) |
|---|---|
| Mass | 197.69 Earth masses (0.622 Jupiter masses) |
| Density | 0.32 g/cm³ (Earth: 5.51) |
| Orbital period | 2.71 days |
| Orbital distance | 0.041 AU |
| Equilibrium temperature | 1,671 K (1,398 °C) |
| Stellar irradiation | 1,293.00× Earth |
| Distance from Earth | 1,747.2 light-years (535.7 parsecs) |
| Constellation | Pegasus |
| Discovery method | Transit |
| Discovery facility | SuperWASP |
| Discovery year | 2025 |
Data: NASA Exoplanet Archive, last updated 2025-04-21. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About WASP-102 b
Is WASP-102 b habitable?
No — WASP-102 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is WASP-102 b?
WASP-102 b is about 1,747 light-years from Earth in the constellation Pegasus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 30,750,720 years to get there.
How big is WASP-102 b compared to Earth?
WASP-102 b has 14.91 times the radius of Earth and about 198 times its mass.
How long is a year on WASP-102 b?
One orbit around WASP-102 takes 2.7 Earth days — short enough that 135 of its years would fit into one Earth year.
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