HD 189733 b

Planet· orbits HD 189733

HD 189733 b - a transiting hot Jupiter (~1.1 Jupiter masses) orbiting its star every 2.2 days. Its measured size gives a real density, and Hubble spectroscopy revealed its sky is DEEP BLUE - light scattered by high hazes, possibly laced with silicate 'glass' clouds driven by 8,000 km/h winds. The blue is real measured colour, not a painted surface.

Open in 3D viewSee HD 189733 b in the live, interactive 3D map

Key facts

Mass

2.14 × 10²⁷ kg

1.13 M♃ (359 M⊕)

Radius

80,721 km

12.7× wider than Earth

Surface gravity

22 m/s²

2.24× Earth's gravity

Year

2.22 Earth days

Distance from HD 189733

4,676,429 km

Science

Physical

Mass: 2.14 × 10²⁷ kg · 1.13 M♃ (359 M⊕)
Radius: 80,721 km · 12.7× wider than Earth
Density: 974 kg/m³ · 0.97× water; Computed from mass and radius
Surface gravity: 22 m/s² · 2.24× Earth's gravity; Computed from mass and radius
Escape velocity: 59.6 km/s · 5.32× Earth's escape velocity; Computed from mass and radius

Orbital

Semi-major axis: 4,676,429 km; From the NASA Exoplanet Archive (transit + radial-velocity orbit)
Eccentricity: 0; From the NASA Exoplanet Archive (transit + radial-velocity orbit)
Inclination: 0.00 °; From the NASA Exoplanet Archive (transit + radial-velocity orbit)
Orbital period: 2.2 days; From the NASA Exoplanet Archive (transit + radial-velocity orbit)
Perihelion: 4,676,429 km; Computed from the orbital elements
Aphelion: 4,676,429 km; Computed from the orbital elements
Mean orbital velocity: 153 km/s; Computed from the orbital elements

Composition

Bulk composition: A hot Jupiter of ~1.1 Jupiter masses — because it transits, its size and density are measured. Hubble found its visible colour to be DEEP BLUE: sunlight scattered by high hazes, likely laced with silicate 'glass' clouds blown by ~8,000 km/h winds. The blue is a real measurement (2013), so the map's blue tint is honest — but the cloud tops themselves have never been imaged.
Cloud appearance: Appearance based on ESO/M. Kornmesser'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: 354 S⊕ · 354× the sunlight Earth receives; Computed from HD 189733's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
Equilibrium temperature: 1,209 K (936 °C); Computed model value for its 2.2-day orbit; its dayside has also been mapped directly by Spitzer — this is the model figure.

Discovery & history

Method: Transit detection
Name: Designated 'b' under the IAU convention that letters a star's planets 'b', 'c', 'd'... in the order they are discovered (the star itself is the unwritten 'a').

Discovered transiting in 2005, its brightness made it a pioneer target: the first exoplanet temperature map (2007), the first detection of an exoplanet's visible colour (blue, Hubble 2013), and detailed wind and molecule measurements. Its surface itself has never been imaged.

Images

Artist's impression of HD 189733 b, whose deep-blue colour was measured by Hubble — an artist's concept, not a photograph. — NASA, ESA & M. Kornmesser (CC BY 4.0) · Wikimedia Commons

NASA 'Galaxy of Horrors' poster for HD 189733 b — 'Rains of Terror'. Stylised Halloween artwork evoking its sideways glass rain, NOT a scientific image of the planet. — NASA/JPL-Caltech (public domain) · Wikimedia Commons

Images from open archives · credit shown per image