awarehorizon // atlas_record
HD 189733 b
A hot giant whose clouds may be mineral, not water.
- classification
- Hot Jupiter exoplanet
- system
- HD 189733
HD 189733 b is a gas giant orbiting a nearby star every 2.2 days. Its short orbit and bright host make it one of the most intensively studied exoplanet atmospheres.
- Distance from Earth
- about 64.5 light years
- Radius
- roughly 1.13 times Jupiter's radius
- Orbital period
- 2.22 days
- Orbital distance
- about 0.031 AU from its star
- Dayside temperature
- roughly 1,200 K, inferred from thermal emission
Only values with an established scientific consensus are listed. Where a quantity is uncertain or model-dependent, it is discussed in the sections below rather than stated as data.
It transits its star
The planet passes in front of the star from our line of sight, allowing its size and atmosphere to be measured.
The atmosphere scatters blue light
Transmission spectra show a steep slope towards shorter wavelengths, consistent with scattering by fine high-altitude particles.
The atmosphere is hot and redistributes heat
Thermal phase curves show the night side is hot too, implying strong winds carry energy around the planet.
Transit spectroscopy
Comparing starlight during and outside transit reveals which wavelengths the atmosphere absorbs.
Radial velocity
The star's periodic motion along our line of sight constrains the planet's mass.
Thermal phase curves
Tracking infrared brightness across a full orbit maps how heat is distributed.
- What exactly are the cloud particles?Silicate grains are a leading hypothesis — the popular 'glass rain' image is an inference, not an observation.
- How fast are the winds really?Published speeds are model-dependent.
- How is the atmosphere structured vertically, and how much is it escaping?
Items above are unresolved. Hypotheses are labelled as such and are not presented as confirmed findings.