Habitable-zone candidate
Kepler-186
First Earth-sized planet found in another star's habitable zone (2014).
- Planets
- 5
- Distance
- 579.2 ly
- Host
- M-type
About Kepler-186
Discovery
Announced on 17 April 2014 by a team led by Elisa Quintana at NASA Ames, Kepler-186f was the first Earth-sized planet confirmed in the habitable zone of another star — the headline result of NASA's Kepler transit survey.
Why it matters
Before Kepler-186f, every habitable-zone candidate was substantially larger than Earth. This discovery proved that genuinely Earth-sized worlds exist in habitable zones, validating a key premise of the search for life elsewhere.
Current research
The host star is too faint and distant for current atmospheric follow-up; Kepler-186f's role today is statistical — anchoring occurrence-rate estimates for Earth analogs around M dwarfs.
Comparable to
About the same size as Earth (1.1 R⊕) but receives only ~32% of the sunlight Earth does — closer to the chill of Mars than the warmth of home.
System geometry
At a glance
- Hostname
- Kepler-186
- Spectral type
- M1
- Distance
- 579.2 ly · 177.59 pc
- Stellar mass
- 0.48 M☉
- Stellar radius
- 0.47 R☉
- Luminosity
- 0.041 L☉
- Effective temp
- 3788 K
- Confirmed planets
- 5
- Habitable zone
- 0.193 – 0.278 AU
Top-down orbital diagram
Orbits to scale within this system. Dashed green = habitable-zone edges.
Planet positions are illustrative (evenly spaced in phase). For live motion see the 3D scene.
The planets
5 confirmed.
Rocky world
Kepler-186 b
- Orbit
- 0.034 AU
- Period
- 3.89 days
- Radius
- 1.07 R⊕
- Mass
- 1.24 M⊕
- Eq. temperature
- 571 K
- Eccentricity
- 0.000
- Discovered
- 2014 · Transit
Rocky world
Kepler-186 c
- Orbit
- 0.045 AU
- Period
- 7.27 days
- Radius
- 1.25 R⊕
- Mass
- 2.10 M⊕
- Eq. temperature
- 464 K
- Eccentricity
- 0.000
- Discovered
- 2014 · Transit
Rocky world
Kepler-186 d
- Orbit
- 0.078 AU
- Period
- 13.34 days
- Radius
- 1.40 R⊕
- Mass
- 2.54 M⊕
- Eq. temperature
- 379 K
- Eccentricity
- 0.000
- Discovered
- 2014 · Transit
Rocky world
Kepler-186 e
- Orbit
- 0.110 AU
- Period
- 22.41 days
- Radius
- 1.27 R⊕
- Mass
- 2.15 M⊕
- Eq. temperature
- 319 K
- Eccentricity
- 0.000
- Discovered
- 2014 · Transit
Ice world
Kepler-186 f
- Orbit
- 0.432 AU
- Period
- 129.94 days
- Radius
- 1.17 R⊕
- Mass
- 1.71 M⊕
- Eq. temperature
- 177 K
- Eccentricity
- 0.040
- Discovered
- 2014 · Transit
Compared to our Solar System
Each row shows the closest Solar-System analog by radius (log-space). Earth is pinned at the bottom as the constant frame of reference.
| Planet | Radius (R⊕) | Mass (M⊕) | Orbit (AU) | Period (days) | Eq temp (K) | Solar analog |
|---|---|---|---|---|---|---|
| Kepler-186 b | 1.07 | 1.24 | 0.034 | 3.89 | 571 | Earth |
| Kepler-186 c | 1.25 | 2.10 | 0.045 | 7.27 | 464 | Earth |
| Kepler-186 d | 1.40 | 2.54 | 0.078 | 13.34 | 379 | Earth |
| Kepler-186 e | 1.27 | 2.15 | 0.110 | 22.41 | 319 | Earth |
| Kepler-186 f | 1.17 | 1.71 | 0.432 | 129.94 | 177 | Earth |
| Earth (reference) | 1.00 | 1.00 | 1.000 | 365.25 | 255 | — |
Research status
◇ JWST observation status
No JWST programs are currently targeting planets in this system. The system may be observed in future cycles or by upcoming missions (Ariel, HWO, Roman).
Discovery timeline
- 2014
5 planets: b, c, d, e, f
via Transit
If you liked this
Other systems in the same theme:
TRAPPIST-1
7 planets · 40.5 ly · M8.0 V
Seven Earth-sized planets around an ultracool dwarf — three in the habitable zone.
Proxima Centauri
2 planets · 4.2 ly · M5.5 V
Our nearest stellar neighbour hosts a potentially habitable terrestrial world.
Kepler-442
1 planets · 1193.6 ly · G2V
One of the most "Earth-like" planets ever found by Kepler — 60% bigger, in HZ.
Experience it
See Kepler-186 in interactive 3D
Fly through the system, click any planet, watch orbits play out at 100× speed.
▶ Launch 3D scene