The star
The star
Kepler-178
- Type
- yellow star
- Surface
- ≈ 5,676 K
- Size
- 1.07 × the Sun
- Mass
- 0.85 × the Sun
- Brightness
- 0.62 × the Sun
- Habitable zone
- 0.594–1.4 AU
The planets
Kepler-178
Kepler-178 b
- Year
- 9.58 days
- Distance from star
- 0.085 AU
- Mass
- 8.8 Earths
- Size
- 2.9 × Earth
- Temperature
- ≈ 846 K (+573 °C)
- Found
- 2014, transit (Kepler)
Kepler-178
Kepler-178 c
- Year
- 20.55 days
- Distance from star
- 0.142 AU
- Mass
- 8.7 Earths
- Size
- 2.9 × Earth
- Temperature
- ≈ 656 K (+383 °C)
- Found
- 2014, transit (Kepler)
Kepler-178
Kepler-178 d
- Year
- 96.68 days
- Distance from star
- 0.397 AU
- Mass
- 15 Earths
- Size
- 4 × Earth
- Temperature
- ≈ 392 K (+119 °C)
- Found
- 2014, 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.