WASP-33 b
WASP-33 b is a hot Jupiter orbiting WASP-33 in the constellation Andromeda. It lies about 398 light-years from Earth and was discovered in 2010 using the transit method.
How Big Is WASP-33 b?
WASP-33 b has a radius of 17.86 times that of Earth, or 1.59 times the radius of Jupiter. Its mass is 665 times that of Earth, giving it a density of 0.69 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is WASP-33 b in the Habitable Zone?
The position of WASP-33 b relative to the habitable zone of WASP-33 cannot be precisely determined from the available orbital data.
Temperature on WASP-33 b
The equilibrium temperature of WASP-33 b is about 2,782 K (2,509 °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-33 b — one full orbit around WASP-33 — lasts just 29.3 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.024 AU — closer to its star than Mercury is to the Sun.
How Was WASP-33 b Discovered?
WASP-33 b was discovered in 2010 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-33 b?
WASP-33 b is 397.7 light-years (121.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1629. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 6,999,520 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-33 b scores 0.05, ranking #5,268 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: WASP-33
WASP-33 b belongs to a system of 2 stars; it orbits WASP-33.
WASP-33
- Surface temperature
- 7,430 K (Sun: 5,772 K)
- Mass
- 1.50 M☉
- Radius
- 1.44 R☉
Planetary System
WASP-33 b is the only planet known to orbit WASP-33 so far.
WASP-33 b — Complete Data
| Radius | 17.856 Earth radii (1.593 Jupiter radii) |
|---|---|
| Mass | 665.22 Earth masses (2.093 Jupiter masses) |
| Density | 0.69 g/cm³ (Earth: 5.51) |
| Orbital period | 1.22 days |
| Orbital distance | 0.024 AU |
| Equilibrium temperature | 2,782 K (2,509 °C) |
| Earth Similarity Index | 0.05 |
| Distance from Earth | 397.7 light-years (121.9 parsecs) |
| Constellation | Andromeda |
| Discovery method | Transit |
| Discovery facility | SuperWASP |
| Discovery year | 2010 |
Data: NASA Exoplanet Archive, last updated 2019-07-08. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About WASP-33 b
Is WASP-33 b habitable?
WASP-33 b is not known to orbit within the habitable zone of WASP-33, and as a hot Jupiter it is an unlikely candidate for life as we know it.
How far away is WASP-33 b?
WASP-33 b is about 398 light-years from Earth in the constellation Andromeda. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,999,520 years to get there.
How big is WASP-33 b compared to Earth?
WASP-33 b has 17.86 times the radius of Earth and about 665 times its mass.
How long is a year on WASP-33 b?
One orbit around WASP-33 takes 1.2 Earth days — short enough that 299 of its years would fit into one Earth year.
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