Record-holder
HD 189733
A blue planet — but the colour comes from glass rain in the upper atmosphere.
- Planets
- 1
- Distance
- 64.5 ly
- Host
- K-type
About HD 189733
Discovery
HD 189733 b was discovered in 2005 by the ELODIE radial-velocity survey (Bouchy et al.) and quickly recognized as a transiting hot Jupiter around a bright K2V star just 64 light-years away.
Why it matters
In 2013, Hubble's STIS instrument measured HD 189733 b's visible-light albedo and concluded the planet would appear deep cobalt blue — the first time astronomers determined the true color of an exoplanet. The blue comes from Rayleigh scattering off high-altitude silicate haze, not water.
Current research
JWST and HST continue to probe its atmospheric chemistry; recent work has refined water, carbon monoxide, and methane abundances and detected variable haze.
Comparable to
A hot Jupiter that looks like a deep-blue marble from space — but instead of oceans, the colour comes from sideways winds raining tiny silicate droplets.
System geometry
At a glance
- Hostname
- HD 189733
- Spectral type
- K2 V
- Distance
- 64.5 ly · 19.76 pc
- Stellar mass
- 0.79 M☉
- Stellar radius
- 0.75 R☉
- Luminosity
- 0.346 L☉
- Effective temp
- 5052 K
- Confirmed planets
- 1
- Habitable zone
- 0.559 – 0.806 AU
Top-down orbital diagram
Orbits to scale within this system. Dashed green = habitable-zone edges.
Planet positions are illustrative (evenly spaced in phase). For live motion see the 3D scene.
The planets
1 confirmed.
Gas giant
HD 189733 b
- Orbit
- 0.031 AU
- Period
- 2.22 days
- Radius
- 12.67 R⊕
- Mass
- 359.15 M⊕
- Eq. temperature
- 1209 K
- Eccentricity
- 0.000
- Discovered
- 2005 · Radial Velocity
Compared to our Solar System
Each row shows the closest Solar-System analog by radius (log-space). Earth is pinned at the bottom as the constant frame of reference.
| Planet | Radius (R⊕) | Mass (M⊕) | Orbit (AU) | Period (days) | Eq temp (K) | Solar analog |
|---|---|---|---|---|---|---|
| HD 189733 b | 12.67 | 359.15 | 0.031 | 2.22 | 1209 | Jupiter |
| Earth (reference) | 1.00 | 1.00 | 1.000 | 365.25 | 255 | — |
Research status
◇ JWST observation status
1 planet has confirmed JWST observation time across Cycles 1–3.
- HD 189733 b
JWST programs include transit spectroscopy, thermal phase curves, and direct imaging coronagraph observations depending on planet class.
Discovery timeline
- 2005
HD 189733 b
via Radial Velocity
If you liked this
Other systems in the same theme:
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3 planets · 1956.9 ly · G2V
First exoplanets ever confirmed (1992) — orbiting a pulsar, not a normal star.
Kepler-16
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A real-world Tatooine — a planet orbiting two stars at once.
GJ 1132
2 planets · 41.1 ly · M4.5 V
A Venus analog 41 ly away — terrestrial world losing its atmosphere.
Experience it
See HD 189733 in interactive 3D
Fly through the system, click any planet, watch orbits play out at 100× speed.
▶ Launch 3D scene