WASP-155 b
WASP-155 b is a hot Jupiter orbiting WASP-155 in the constellation Pegasus. It lies about 1,303 light-years from Earth and was discovered in 2025 using the transit method.
How Big Is WASP-155 b?
WASP-155 b has a radius of 13.45 times that of Earth, or 1.20 times the radius of Jupiter. Its mass is 277 times that of Earth, giving it a density of 0.62 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is WASP-155 b in the Habitable Zone?
WASP-155 b orbits inside the inner edge of the habitable zone of WASP-155. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of WASP-155: 0.899–2.126 AU (conservative: 1.139–2.015 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on WASP-155 b
The equilibrium temperature of WASP-155 b is about 1,468 K (1,195 °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 771 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on WASP-155 b — one full orbit around WASP-155 — lasts 3.11 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.043 AU — closer to its star than Mercury is to the Sun.
How Was WASP-155 b Discovered?
WASP-155 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-155 b?
WASP-155 b is 1,303.4 light-years (399.6 parsecs) from Earth. Light arriving here tonight left the planet about 1,303 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 22,939,840 years to make the journey.
The Host Star: WASP-155
WASP-155
- Surface temperature
- 5,660 K (Sun: 5,772 K)
- Mass
- 1.09 M☉
- Radius
- 1.24 R☉
- Age
- 1.7 billion years (Sun: 4.6)
Planetary System
WASP-155 b is the only planet known to orbit WASP-155 so far.
WASP-155 b — Complete Data
| Radius | 13.451 Earth radii (1.200 Jupiter radii) |
|---|---|
| Mass | 276.83 Earth masses (0.871 Jupiter masses) |
| Density | 0.62 g/cm³ (Earth: 5.51) |
| Orbital period | 3.11 days |
| Orbital distance | 0.043 AU |
| Equilibrium temperature | 1,468 K (1,195 °C) |
| Stellar irradiation | 771.00× Earth |
| Distance from Earth | 1,303.4 light-years (399.6 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-155 b
Is WASP-155 b habitable?
No — WASP-155 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is WASP-155 b?
WASP-155 b is about 1,303 light-years from Earth in the constellation Pegasus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 22,939,840 years to get there.
How big is WASP-155 b compared to Earth?
WASP-155 b has 13.45 times the radius of Earth and about 277 times its mass.
How long is a year on WASP-155 b?
One orbit around WASP-155 takes 3.1 Earth days — short enough that 117 of its years would fit into one Earth year.
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