Kepler-338 d
Kepler-338 d is a mini-Neptune orbiting Kepler-338 in the constellation Lyra. It lies about 1,803 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-338 d?
Kepler-338 d has a radius of 3.00 times that of Earth.
Is Kepler-338 d in the Habitable Zone?
Kepler-338 d orbits inside the inner edge of the habitable zone of Kepler-338. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-338: 1.356–3.184 AU (conservative: 1.718–3.018 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-338 d — one full orbit around Kepler-338 — lasts 44.4 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.257 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-338 d Discovered?
Kepler-338 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-338 d?
Kepler-338 d is 1,803.0 light-years (552.8 parsecs) from Earth. Light arriving here tonight left the planet about 1,803 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 31,732,800 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-338 d scores 0.23, ranking #3,499 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-338
Kepler-338
- Surface temperature
- 5,923 K (Sun: 5,772 K)
- Radius
- 1.74 R☉
The Kepler-338 Planetary System
Kepler-338 d is one of 4 known planets in the Kepler-338 system. Its siblings:
- Kepler-338 b (Mini Neptune)
- Kepler-338 c (Mini Neptune)
- Kepler-338 e (Super Earth)
Kepler-338 d — Complete Data
| Radius | 3.000 Earth radii (0.268 Jupiter radii) |
|---|---|
| Orbital period | 44.43 days |
| Orbital distance | 0.257 AU |
| Earth Similarity Index | 0.23 |
| Distance from Earth | 1,803.0 light-years (552.8 parsecs) |
| Constellation | Lyra |
| 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-338 d
Is Kepler-338 d habitable?
No — Kepler-338 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-338 d?
Kepler-338 d is about 1,803 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 31,732,800 years to get there.
How big is Kepler-338 d compared to Earth?
Kepler-338 d has 3.00 times the radius of Earth.
How long is a year on Kepler-338 d?
One orbit around Kepler-338 takes 44.4 Earth days.
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