Kepler-639 b
Kepler-639 b is a mini-Neptune orbiting Kepler-639 in the constellation Cygnus. It lies about 2,773 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is Kepler-639 b?
Kepler-639 b has a radius of 2.38 times that of Earth.
Is Kepler-639 b in the Habitable Zone?
The position of Kepler-639 b relative to the habitable zone of Kepler-639 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-639: 1.001–2.351 AU (conservative: 1.268–2.229 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-639 b — one full orbit around Kepler-639 — lasts 10.2 Earth days, shorter than Mercury's 88-day year.
How Was Kepler-639 b Discovered?
Kepler-639 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-639 b?
Kepler-639 b is 2,773.1 light-years (850.2 parsecs) from Earth. Light arriving here tonight left the planet about 2,773 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 48,806,560 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-639 b scores 0.24, ranking #3,302 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-639
Kepler-639
- Surface temperature
- 5,896 K (Sun: 5,772 K)
- Mass
- 1.14 M☉
- Radius
- 1.29 R☉
- Age
- 4.4 billion years (Sun: 4.6)
Planetary System
Kepler-639 b is the only planet known to orbit Kepler-639 so far.
Kepler-639 b — Complete Data
| Radius | 2.380 Earth radii (0.212 Jupiter radii) |
|---|---|
| Orbital period | 10.21 days |
| Earth Similarity Index | 0.24 |
| Distance from Earth | 2,773.1 light-years (850.2 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-639 b
Is Kepler-639 b habitable?
Kepler-639 b is not known to orbit within the habitable zone of Kepler-639, and as a mini-Neptune it is an unlikely candidate for life as we know it.
How far away is Kepler-639 b?
Kepler-639 b is about 2,773 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 48,806,560 years to get there.
How big is Kepler-639 b compared to Earth?
Kepler-639 b has 2.38 times the radius of Earth.
How long is a year on Kepler-639 b?
One orbit around Kepler-639 takes 10.2 Earth days — short enough that 36 of its years would fit into one Earth year.
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