The star
The star
Kepler-33
- Type
- yellow star
- Surface
- ≈ 5,904 K
- Size
- 1.82 × the Sun
- Mass
- 1.29 × the Sun
- Brightness
- 3.6 × the Sun
- Habitable zone
- 1.41–3.32 AU
The planets
Kepler-33
Kepler-33 b
- Year
- 5.67 days
- Distance from star
- 0.0677 AU
- Mass
- 3.7 Earths
- Size
- 1.7 × Earth
- Temperature
- ≈ 1336 K (+1063 °C)
- Found
- 2011, transit (Kepler)
Kepler-33
Kepler-33 c
- Year
- 13.18 days
- Distance from star
- 0.119 AU
- Mass
- 0.39 Earths
- Size
- 3.2 × Earth
- Temperature
- ≈ 1009 K (+736 °C)
- Found
- 2011, transit (Kepler)
Kepler-33
Kepler-33 d
- Year
- 21.78 days
- Distance from star
- 0.166 AU
- Mass
- 3.9 Earths
- Size
- 5.3 × Earth
- Temperature
- ≈ 853 K (+580 °C)
- Found
- 2011, transit (Kepler)
Kepler-33
Kepler-33 e
- Year
- 31.78 days
- Distance from star
- 0.214 AU
- Mass
- 5.6 Earths
- Size
- 4 × Earth
- Temperature
- ≈ 752 K (+479 °C)
- Found
- 2011, transit (Kepler)
Kepler-33
Kepler-33 f
- Year
- 41.03 days
- Distance from star
- 0.254 AU
- Mass
- 9.6 Earths
- Size
- 4.5 × Earth
- Temperature
- ≈ 691 K (+418 °C)
- Found
- 2011, transit (Kepler)
Masses found by the wobble method are minimums, because the orbit's tilt is unknown. Temperatures are equilibrium estimates for a bare planet, before any atmosphere.
How we know
The shadow
The planet passes in front of its star and dims it by a fraction of a percent, every orbit. The dip gives the planet's size and year.
Sources
- Planet and star parameters: NASA Exoplanet Archive, Planetary Systems Composite Parameters, retrieved 1 Nov 2026. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with NASA under the Exoplanet Exploration Program.
- Position: HYG Database v4.1 (CC BY-SA 4.0).
- Habitable zone: a simple estimate from the star's brightness (√L × 0.95 to 1.67 AU), shown as a guide.