WASP-89 b
WASP-89 b is a hot Jupiter orbiting the K3 star WASP-89 in the constellation Capricornus. It lies about 949 light-years from Earth and was discovered in 2015 using the transit method.
How Big Is WASP-89 b?
WASP-89 b has a radius of 11.66 times that of Earth, or 1.04 times the radius of Jupiter. Its mass is 1,875 times that of Earth, giving it a density of 7.00 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is WASP-89 b in the Habitable Zone?
WASP-89 b orbits inside the inner edge of the habitable zone of WASP-89. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of WASP-89: 0.540–1.299 AU (conservative: 0.684–1.231 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on WASP-89 b
The equilibrium temperature of WASP-89 b is about 1,120 K (847 °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-89 b — one full orbit around WASP-89 — lasts 3.36 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. Its orbit is mildly elliptical (eccentricity 0.19).
How Was WASP-89 b Discovered?
WASP-89 b was discovered in 2015 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-89 b?
WASP-89 b is 948.9 light-years (290.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1078. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 16,700,640 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-89 b scores 0.08, ranking #4,667 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: WASP-89
WASP-89
- Spectral type
- K3
- Surface temperature
- 5,130 K (Sun: 5,772 K)
- Mass
- 0.92 M☉
- Radius
- 0.88 R☉
- Age
- 1.3 billion years (Sun: 4.6)
Planetary System
WASP-89 b is the only planet known to orbit WASP-89 so far.
WASP-89 b — Complete Data
| Radius | 11.657 Earth radii (1.040 Jupiter radii) |
|---|---|
| Mass | 1,875.20 Earth masses (5.900 Jupiter masses) |
| Density | 7.00 g/cm³ (Earth: 5.51) |
| Orbital period | 3.36 days |
| Orbital distance | 0.043 AU |
| Eccentricity | 0.193 |
| Equilibrium temperature | 1,120 K (847 °C) |
| Earth Similarity Index | 0.08 |
| Distance from Earth | 948.9 light-years (290.9 parsecs) |
| Constellation | Capricornus |
| Discovery method | Transit |
| Discovery facility | SuperWASP |
| Discovery year | 2015 |
Data: NASA Exoplanet Archive, last updated 2015-07-08. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About WASP-89 b
Is WASP-89 b habitable?
No — WASP-89 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is WASP-89 b?
WASP-89 b is about 949 light-years from Earth in the constellation Capricornus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 16,700,640 years to get there.
How big is WASP-89 b compared to Earth?
WASP-89 b has 11.66 times the radius of Earth and about 1,875 times its mass.
How long is a year on WASP-89 b?
One orbit around WASP-89 takes 3.4 Earth days — short enough that 109 of its years would fit into one Earth year.
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