Kepler-186 f
The parameters of this planet are disputed or ambiguous in the scientific literature.
Kepler-186 f is a terrestrial planet orbiting the M1 star Kepler-186 in the constellation Cygnus. It lies about 579 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-186 f?
Kepler-186 f has a radius of 1.17 times that of Earth.
Is Kepler-186 f in the Habitable Zone?
Kepler-186 f orbits beyond the outer edge of the habitable zone of Kepler-186. At that distance, any surface water would almost certainly be frozen.
Habitable zone of Kepler-186: 0.165–0.423 AU (conservative: 0.209–0.401 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on Kepler-186 f
Kepler-186 f receives 0.30 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on Kepler-186 f — one full orbit around Kepler-186 — lasts 129.9 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.432 AU — comparable to the inner Solar System. Its orbit is nearly circular (eccentricity 0.040).
How Was Kepler-186 f Discovered?
Kepler-186 f 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-186 f?
Kepler-186 f is 579.2 light-years (177.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1447. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 10,193,920 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-186 f scores 0.61, ranking #125 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-186
Kepler-186
- Spectral type
- M1
- Surface temperature
- 3,788 K (Sun: 5,772 K)
- Mass
- 0.48 M☉
- Radius
- 0.47 R☉
- Luminosity
- 0.0412 L☉
- Age
- 4.0 billion years (Sun: 4.6)
The Kepler-186 Planetary System
Kepler-186 f is one of 5 known planets in the Kepler-186 system. Its siblings:
- Kepler-186 b (Terrestrial)
- Kepler-186 c (Terrestrial)
- Kepler-186 d (Super Earth)
- Kepler-186 e (Super Earth)
Kepler-186 f — Complete Data
| Radius | 1.170 Earth radii (0.104 Jupiter radii) |
|---|---|
| Orbital period | 129.94 days |
| Orbital distance | 0.432 AU |
| Eccentricity | 0.040 |
| Stellar irradiation | 0.30× Earth |
| Earth Similarity Index | 0.61 |
| Distance from Earth | 579.2 light-years (177.6 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2014 |
Data: NASA Exoplanet Archive, last updated 2015-01-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-186 f
Is Kepler-186 f habitable?
No — Kepler-186 f orbits outside the habitable zone of Kepler-186 and is likely too cold for liquid water on its surface.
How far away is Kepler-186 f?
Kepler-186 f is about 579 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 10,193,920 years to get there.
How big is Kepler-186 f compared to Earth?
Kepler-186 f has 1.17 times the radius of Earth.
How long is a year on Kepler-186 f?
One orbit around Kepler-186 takes 129.9 Earth days.
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