WASP-118 b
WASP-118 b is a hot Jupiter orbiting the F6 star WASP-118 in the constellation Pisces. It lies about 1,229 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is WASP-118 b?
WASP-118 b has a radius of 16.14 times that of Earth, or 1.44 times the radius of Jupiter. Its mass is 163 times that of Earth, giving it a density of 0.23 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is WASP-118 b in the Habitable Zone?
WASP-118 b orbits inside the inner edge of the habitable zone of WASP-118. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of WASP-118: 1.508–3.504 AU (conservative: 1.910–3.323 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on WASP-118 b
The equilibrium temperature of WASP-118 b is about 1,729 K (1,456 °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-118 b — one full orbit around WASP-118 — lasts 4.05 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.055 AU — closer to its star than Mercury is to the Sun.
How Was WASP-118 b Discovered?
WASP-118 b was discovered in 2016 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-118 b?
WASP-118 b is 1,228.5 light-years (376.7 parsecs) from Earth. Light arriving here tonight left the planet about 1,229 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 21,621,600 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-118 b scores 0.06, ranking #5,201 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: WASP-118
WASP-118
- Spectral type
- F6
- Surface temperature
- 6,410 K (Sun: 5,772 K)
- Mass
- 1.32 M☉
- Radius
- 1.70 R☉
- Age
- 1.2 billion years (Sun: 4.6)
Planetary System
WASP-118 b is the only planet known to orbit WASP-118 so far.
WASP-118 b — Complete Data
| Radius | 16.141 Earth radii (1.440 Jupiter radii) |
|---|---|
| Mass | 163.36 Earth masses (0.514 Jupiter masses) |
| Density | 0.23 g/cm³ (Earth: 5.51) |
| Orbital period | 4.05 days |
| Orbital distance | 0.055 AU |
| Equilibrium temperature | 1,729 K (1,456 °C) |
| Earth Similarity Index | 0.06 |
| Distance from Earth | 1,228.5 light-years (376.7 parsecs) |
| Constellation | Pisces |
| Discovery method | Transit |
| Discovery facility | SuperWASP |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2016-09-06. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About WASP-118 b
Is WASP-118 b habitable?
No — WASP-118 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is WASP-118 b?
WASP-118 b is about 1,229 light-years from Earth in the constellation Pisces. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 21,621,600 years to get there.
How big is WASP-118 b compared to Earth?
WASP-118 b has 16.14 times the radius of Earth and about 163 times its mass.
How long is a year on WASP-118 b?
One orbit around WASP-118 takes 4.0 Earth days — short enough that 90 of its years would fit into one Earth year.
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