Kepler-231 c
Kepler-231 c is a super-Earth orbiting Kepler-231 in the constellation Cygnus. It lies about 1,033 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-231 c?
Kepler-231 c has a radius of 1.93 times that of Earth.
Is Kepler-231 c in the Habitable Zone?
Kepler-231 c orbits inside the inner edge of the habitable zone of Kepler-231. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-231: 0.170–0.435 AU (conservative: 0.215–0.412 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Orbit and Year Length
A year on Kepler-231 c — one full orbit around Kepler-231 — lasts 19.3 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.114 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-231 c Discovered?
Kepler-231 c was discovered in 2014 using the transit method, with observations from Kepler.
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is Kepler-231 c?
Kepler-231 c is 1,032.7 light-years (316.6 parsecs) from Earth. Light arriving here tonight left the planet about 1,033 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 18,175,520 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. Kepler-231 c scores 0.42, ranking #409 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-231
Kepler-231
- Surface temperature
- 3,767 K (Sun: 5,772 K)
- Radius
- 0.49 R☉
The Kepler-231 Planetary System
Kepler-231 c is one of 2 known planets in the Kepler-231 system. Its siblings:
- Kepler-231 b (Super Earth)
Kepler-231 c — Complete Data
| Radius | 1.930 Earth radii (0.172 Jupiter radii) |
|---|---|
| Orbital period | 19.27 days |
| Orbital distance | 0.114 AU |
| Earth Similarity Index | 0.42 |
| Distance from Earth | 1,032.7 light-years (316.6 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2014 |
Data: NASA Exoplanet Archive, last updated 2014-05-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-231 c
Is Kepler-231 c habitable?
No — Kepler-231 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-231 c?
Kepler-231 c is about 1,033 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 18,175,520 years to get there.
How big is Kepler-231 c compared to Earth?
Kepler-231 c has 1.93 times the radius of Earth.
How long is a year on Kepler-231 c?
One orbit around Kepler-231 takes 19.3 Earth days — short enough that 19 of its years would fit into one Earth year.
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