Kepler-991 b
Kepler-991 b is a mini-Neptune orbiting Kepler-991 in the constellation Cygnus. It lies about 1,271 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is Kepler-991 b?
Kepler-991 b has a radius of 2.54 times that of Earth.
Is Kepler-991 b in the Habitable Zone?
The position of Kepler-991 b relative to the habitable zone of Kepler-991 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-991: 0.283–0.702 AU (conservative: 0.358–0.666 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-991 b — one full orbit around Kepler-991 — lasts 82.5 Earth days, shorter than Mercury's 88-day year.
How Was Kepler-991 b Discovered?
Kepler-991 b was discovered in 2016 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-991 b?
Kepler-991 b is 1,270.6 light-years (389.6 parsecs) from Earth. Light arriving here tonight left the planet about 1,271 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 22,362,560 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-991 b scores 0.66, ranking #89 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-991
Kepler-991
- Surface temperature
- 4,392 K (Sun: 5,772 K)
- Mass
- 0.64 M☉
- Radius
- 0.61 R☉
- Age
- 3.5 billion years (Sun: 4.6)
Planetary System
Kepler-991 b is the only planet known to orbit Kepler-991 so far.
Kepler-991 b — Complete Data
| Radius | 2.540 Earth radii (0.227 Jupiter radii) |
|---|---|
| Orbital period | 82.53 days |
| Earth Similarity Index | 0.66 |
| Distance from Earth | 1,270.6 light-years (389.6 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2016-05-06. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-991 b
Is Kepler-991 b habitable?
Kepler-991 b is not known to orbit within the habitable zone of Kepler-991, and as a mini-Neptune it is an unlikely candidate for life as we know it.
How far away is Kepler-991 b?
Kepler-991 b is about 1,271 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 22,362,560 years to get there.
How big is Kepler-991 b compared to Earth?
Kepler-991 b has 2.54 times the radius of Earth.
How long is a year on Kepler-991 b?
One orbit around Kepler-991 takes 82.5 Earth days.
Explore Kepler-991 b in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
