WASP-76 b
Planet· orbits WASP-76
WASP-76 b — a bloated ultra-hot Jupiter (1.85 Jupiter radii, ~0.9 Jupiter masses) orbiting every 1.8 days with a dayside near 2,400°C. It is famous for IRON RAIN: iron vaporises on the scorching day side, blows to the cooler night side, and — models indicate — condenses and falls as droplets of molten iron. Because it transits with a measured mass, its very low density is real. Its clouds have never been imaged.
Open in 3D viewSee WASP-76 b in the live, interactive 3D map
Key facts
Mass
1.70 × 10²⁷ kg
0.894 M♃ (284 M⊕)
Radius
132,389 km
20.8× wider than Earth
Surface gravity
6.46 m/s²
66% of Earth's gravity
Year
1.81 Earth days
Distance from WASP-76
4,936,730 km
Science
Physical
- Mass
- 1.70 × 10²⁷ kg · 0.894 M♃ (284 M⊕)
- Radius
- 132,389 km · 20.8× wider than Earth
- Density
- 175 kg/m³ · 0.17× water
- Computed from mass and radius
- Surface gravity
- 6.46 m/s² · 66% of Earth's gravity
- Computed from mass and radius
- Escape velocity
- 41.4 km/s · 3.7× Earth's escape velocity
- Computed from mass and radius
Orbital
- Semi-major axis
- 4,936,730 km
- From the NASA Exoplanet Archive (transit + orbit fit)
- Eccentricity
- 0
- From the NASA Exoplanet Archive (transit + orbit fit)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (transit + orbit fit)
- Orbital period
- 43.44 hours
- From the NASA Exoplanet Archive (transit + orbit fit)
- Perihelion
- 4,936,730 km
- Computed from the orbital elements
- Aphelion
- 4,936,730 km
- Computed from the orbital elements
- Mean orbital velocity
- 198 km/s
- Computed from the orbital elements
Atmosphere
- Composition
- Hydrogen-dominated with vaporised iron and other metals detected (ESPRESSO, 2020); models indicate iron condenses into rain on the nightside.
Composition
- Bulk composition
- A bloated ultra-hot Jupiter (1.85 Jupiter radii, ~0.9 Jupiter masses, real density from transit + mass). Its dayside is so hot (~2,400°C) that iron vaporises; in 2020 the ESPRESSO spectrograph traced iron vapour vanishing at the day-night boundary — read as iron condensing and raining down as molten droplets on the cooler night side. One of the most vivid pictures of alien weather. Never imaged.
- Cloud appearance
- Appearance based on NASA/JPL-Caltech's artist's concept. No spacecraft has imaged this world, so its real appearance is unknown — The banded clouds shown are a representation of its class, shown only in Visual mode; Realism shows a plain spectral colour.
Radiation & temperature
- Insolation
- 4,093 S⊕ · 4,093× the sunlight Earth receives
- Computed from WASP-76's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 2,228 K (1,955 °C)
- Computed model value (~1,955°C); the dayside is measured hotter, ~2,400°C.
Discovery & history
- Method
- Transit detection
- Name
- Designated 'b' under the IAU convention that letters a star's planets 'b', 'c'… in the order found (the star is the unwritten 'a'); no IAU proper name is assigned.
Found transiting in 2016; in 2020 ESPRESSO on the VLT traced iron vapour vanishing at the day-night boundary — read as iron condensing into rain.
Images
Images from open archives · credit shown per image