Kepler-681 b
Kepler-681 b is a sub-Neptune orbiting Kepler-681 in the constellation Cygnus. It lies about 2,240 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is Kepler-681 b?
Kepler-681 b has a radius of 3.08 times that of Earth.
Is Kepler-681 b in the Habitable Zone?
The position of Kepler-681 b relative to the habitable zone of Kepler-681 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-681: 0.449–1.085 AU (conservative: 0.569–1.029 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-681 b — one full orbit around Kepler-681 — lasts 26.4 Earth days, shorter than Mercury's 88-day year.
How Was Kepler-681 b Discovered?
Kepler-681 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-681 b?
Kepler-681 b is 2,240.4 light-years (686.9 parsecs) from Earth. Light arriving here tonight left the planet about 2,240 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 39,431,040 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-681 b scores 0.29, ranking #1,589 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-681
Kepler-681
- Surface temperature
- 5,021 K (Sun: 5,772 K)
- Mass
- 0.80 M☉
- Radius
- 0.76 R☉
- Age
- 5.0 billion years (Sun: 4.6)
Planetary System
Kepler-681 b is the only planet known to orbit Kepler-681 so far.
Kepler-681 b — Complete Data
| Radius | 3.080 Earth radii (0.275 Jupiter radii) |
|---|---|
| Orbital period | 26.39 days |
| Earth Similarity Index | 0.29 |
| Distance from Earth | 2,240.4 light-years (686.9 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-681 b
Is Kepler-681 b habitable?
Kepler-681 b is not known to orbit within the habitable zone of Kepler-681, and as a sub-Neptune it is an unlikely candidate for life as we know it.
How far away is Kepler-681 b?
Kepler-681 b is about 2,240 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 39,431,040 years to get there.
How big is Kepler-681 b compared to Earth?
Kepler-681 b has 3.08 times the radius of Earth.
How long is a year on Kepler-681 b?
One orbit around Kepler-681 takes 26.4 Earth days — short enough that 14 of its years would fit into one Earth year.
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