Kepler-439 b
Kepler-439 b is a mini-Neptune orbiting Kepler-439 in the constellation Lyra. It lies about 2,469 light-years from Earth and was discovered in 2015 using the transit method.
How Big Is Kepler-439 b?
Kepler-439 b has a radius of 2.24 times that of Earth.
Is Kepler-439 b in the Habitable Zone?
Kepler-439 b orbits inside the inner edge of the habitable zone of Kepler-439. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-439: 0.584–1.389 AU (conservative: 0.739–1.317 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 ›
Temperature on Kepler-439 b
Kepler-439 b receives 1.83 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on Kepler-439 b — one full orbit around Kepler-439 — lasts 178.1 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.563 AU — comparable to the inner Solar System. Its orbit is nearly circular (eccentricity 0.030).
How Was Kepler-439 b Discovered?
Kepler-439 b was discovered in 2015 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-439 b?
Kepler-439 b is 2,469.2 light-years (757.0 parsecs) from Earth. Light arriving here tonight left the planet about 2,469 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 43,457,920 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-439 b scores 0.66, ranking #86 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-439
Kepler-439
- Surface temperature
- 5,431 K (Sun: 5,772 K)
- Mass
- 0.88 M☉
- Radius
- 0.87 R☉
- Luminosity
- 0.5808 L☉
- Age
- 7.2 billion years (Sun: 4.6)
Planetary System
Kepler-439 b is the only planet known to orbit Kepler-439 so far.
Kepler-439 b — Complete Data
| Radius | 2.240 Earth radii (0.200 Jupiter radii) |
|---|---|
| Orbital period | 178.14 days |
| Orbital distance | 0.563 AU |
| Eccentricity | 0.030 |
| Stellar irradiation | 1.83× Earth |
| Earth Similarity Index | 0.66 |
| Distance from Earth | 2,469.2 light-years (757.0 parsecs) |
| Constellation | Lyra |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2015 |
Data: NASA Exoplanet Archive, last updated 2015-01-06. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-439 b
Is Kepler-439 b habitable?
No — Kepler-439 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-439 b?
Kepler-439 b is about 2,469 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 43,457,920 years to get there.
How big is Kepler-439 b compared to Earth?
Kepler-439 b has 2.24 times the radius of Earth.
How long is a year on Kepler-439 b?
One orbit around Kepler-439 takes 178.1 Earth days.
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