Kepler-339 d
Kepler-339 d is a terrestrial planet orbiting Kepler-339 in the constellation Cygnus. It lies about 2,011 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-339 d?
Kepler-339 d has a radius of 1.17 times that of Earth.
Is Kepler-339 d in the Habitable Zone?
Kepler-339 d orbits inside the inner edge of the habitable zone of Kepler-339. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-339: 0.577–1.364 AU (conservative: 0.730–1.293 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-339 d — one full orbit around Kepler-339 — lasts 10.6 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.091 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-339 d Discovered?
Kepler-339 d 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-339 d?
Kepler-339 d is 2,011.2 light-years (616.6 parsecs) from Earth. Light arriving here tonight left the planet about 2,011 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 35,397,120 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-339 d scores 0.31, ranking #1,097 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-339
Kepler-339
- Surface temperature
- 5,631 K (Sun: 5,772 K)
- Radius
- 0.80 R☉
The Kepler-339 Planetary System
Kepler-339 d is one of 3 known planets in the Kepler-339 system. Its siblings:
- Kepler-339 b (Super Earth)
- Kepler-339 c (Terrestrial)
Kepler-339 d — Complete Data
| Radius | 1.170 Earth radii (0.104 Jupiter radii) |
|---|---|
| Orbital period | 10.56 days |
| Orbital distance | 0.091 AU |
| Earth Similarity Index | 0.31 |
| Distance from Earth | 2,011.2 light-years (616.6 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-339 d
Is Kepler-339 d habitable?
No — Kepler-339 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-339 d?
Kepler-339 d is about 2,011 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 35,397,120 years to get there.
How big is Kepler-339 d compared to Earth?
Kepler-339 d has 1.17 times the radius of Earth.
How long is a year on Kepler-339 d?
One orbit around Kepler-339 takes 10.6 Earth days — short enough that 35 of its years would fit into one Earth year.
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