Kepler-23 c
Kepler-23 c is a sub-Neptune orbiting Kepler-23 in the constellation Cygnus. It lies about 2,726 light-years from Earth and was discovered in 2011 using the transit method.
How Big Is Kepler-23 c?
Kepler-23 c has a radius of 3.01 times that of Earth. Its mass is 7.8 times that of Earth, giving it a density of 1.58 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is Kepler-23 c in the Habitable Zone?
The position of Kepler-23 c relative to the habitable zone of Kepler-23 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-23: 1.178–2.773 AU (conservative: 1.493–2.629 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-23 c — one full orbit around Kepler-23 — lasts 10.7 Earth days, shorter than Mercury's 88-day year. Its orbit is nearly circular (eccentricity 0.021).
How Was Kepler-23 c Discovered?
Kepler-23 c was discovered in 2011 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-23 c?
Kepler-23 c is 2,725.9 light-years (835.8 parsecs) from Earth. Light arriving here tonight left the planet about 2,726 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 47,975,840 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-23 c scores 0.21, ranking #3,811 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-23
Kepler-23
- Surface temperature
- 5,828 K (Sun: 5,772 K)
- Mass
- 1.08 M☉
- Radius
- 1.55 R☉
The Kepler-23 Planetary System
Kepler-23 c is one of 3 known planets in the Kepler-23 system. Its siblings:
- Kepler-23 b (Super Earth)
- Kepler-23 d (Mini Neptune)
Kepler-23 c — Complete Data
| Radius | 3.005 Earth radii (0.268 Jupiter radii) |
|---|---|
| Mass | 7.81 Earth masses (0.025 Jupiter masses) |
| Density | 1.58 g/cm³ (Earth: 5.51) |
| Orbital period | 10.74 days |
| Eccentricity | 0.021 |
| Earth Similarity Index | 0.21 |
| Distance from Earth | 2,725.9 light-years (835.8 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2011 |
Data: NASA Exoplanet Archive, last updated 2024-06-10. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-23 c
Is Kepler-23 c habitable?
Kepler-23 c is not known to orbit within the habitable zone of Kepler-23, and as a sub-Neptune it is an unlikely candidate for life as we know it.
How far away is Kepler-23 c?
Kepler-23 c is about 2,726 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 47,975,840 years to get there.
How big is Kepler-23 c compared to Earth?
Kepler-23 c has 3.01 times the radius of Earth and about 7.8 times its mass.
How long is a year on Kepler-23 c?
One orbit around Kepler-23 takes 10.7 Earth days — short enough that 34 of its years would fit into one Earth year.
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