Kepler-191 b
Kepler-191 b is a super-Earth orbiting Kepler-191 in the constellation Cygnus. It lies about 1,939 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-191 b?
Kepler-191 b has a radius of 1.34 times that of Earth.
Is Kepler-191 b in the Habitable Zone?
Kepler-191 b orbits inside the inner edge of the habitable zone of Kepler-191. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-191: 0.509–1.218 AU (conservative: 0.645–1.155 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Orbit and Year Length
A year on Kepler-191 b — one full orbit around Kepler-191 — lasts 9.94 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.087 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-191 b Discovered?
Kepler-191 b 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-191 b?
Kepler-191 b is 1,938.9 light-years (594.5 parsecs) from Earth. Light arriving here tonight left the planet about 1,939 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 34,124,640 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-191 b scores 0.31, ranking #1,119 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-191
Kepler-191
- Surface temperature
- 5,282 K (Sun: 5,772 K)
- Radius
- 0.79 R☉
The Kepler-191 Planetary System
Kepler-191 b is one of 3 known planets in the Kepler-191 system. Its siblings:
- Kepler-191 c (Super Earth)
- Kepler-191 d (Mini Neptune)
Kepler-191 b — Complete Data
| Radius | 1.340 Earth radii (0.120 Jupiter radii) |
|---|---|
| Orbital period | 9.94 days |
| Orbital distance | 0.087 AU |
| Earth Similarity Index | 0.31 |
| Distance from Earth | 1,938.9 light-years (594.5 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-191 b
Is Kepler-191 b habitable?
No — Kepler-191 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-191 b?
Kepler-191 b is about 1,939 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 34,124,640 years to get there.
How big is Kepler-191 b compared to Earth?
Kepler-191 b has 1.34 times the radius of Earth.
How long is a year on Kepler-191 b?
One orbit around Kepler-191 takes 9.9 Earth days — short enough that 37 of its years would fit into one Earth year.
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