The star
The star
Kepler-42
- Type
- M
- Surface
- ≈ 3,068 K
- Size
- 0.17 × the Sun
- Mass
- 0.13 × the Sun
- Brightness
- 0.0024 × the Sun
- Habitable zone
- 0.0402–0.107 AU
The planets
Kepler-42
Kepler-42 c
- Year
- 0.45 days
- Distance from star
- 0.006 AU
- Mass
- 60 Earths
- Size
- 0.73 × Earth
- Temperature
- ≈ 720 K (+447 °C)
- Found
- 2011, transit (Kepler)
Kepler-42
Kepler-42 b
- Year
- 1.21 days
- Distance from star
- 0.0116 AU
- Mass
- 0.71 Earths
- Size
- 0.78 × Earth
- Temperature
- ≈ 519 K (+246 °C)
- Found
- 2011, transit (Kepler)
Kepler-42
Kepler-42 d
- Year
- 1.87 days
- Distance from star
- 0.0154 AU
- Mass
- 0.36 Earths
- Size
- 0.57 × Earth
- Temperature
- ≈ 450 K (+177 °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.