Kepler-171 c
Kepler-171 c is a mini-Neptune orbiting Kepler-171 in the constellation Cygnus. It lies about 2,818 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-171 c?
Kepler-171 c has a radius of 2.56 times that of Earth.
Is Kepler-171 c in the Habitable Zone?
Kepler-171 c orbits inside the inner edge of the habitable zone of Kepler-171. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-171: 0.605–1.431 AU (conservative: 0.767–1.357 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-171 c — one full orbit around Kepler-171 — lasts 11.5 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.098 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-171 c Discovered?
Kepler-171 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-171 c?
Kepler-171 c is 2,817.5 light-years (863.9 parsecs) from Earth. Light arriving here tonight left the planet about 2,818 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 49,588,000 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-171 c scores 0.24, ranking #3,259 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-171
Kepler-171
- Surface temperature
- 5,642 K (Sun: 5,772 K)
- Radius
- 0.84 R☉
The Kepler-171 Planetary System
Kepler-171 c is one of 3 known planets in the Kepler-171 system. Its siblings:
- Kepler-171 b (Mini Neptune)
- Kepler-171 d (Super Earth)
Kepler-171 c — Complete Data
| Radius | 2.560 Earth radii (0.228 Jupiter radii) |
|---|---|
| Orbital period | 11.46 days |
| Orbital distance | 0.098 AU |
| Earth Similarity Index | 0.24 |
| Distance from Earth | 2,817.5 light-years (863.9 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-171 c
Is Kepler-171 c habitable?
No — Kepler-171 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-171 c?
Kepler-171 c is about 2,818 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 49,588,000 years to get there.
How big is Kepler-171 c compared to Earth?
Kepler-171 c has 2.56 times the radius of Earth.
How long is a year on Kepler-171 c?
One orbit around Kepler-171 takes 11.5 Earth days — short enough that 32 of its years would fit into one Earth year.
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