Kepler-238 d
Kepler-238 d is a sub-Neptune orbiting Kepler-238 in the constellation Lyra. It lies about 5,867 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-238 d?
Kepler-238 d has a radius of 3.07 times that of Earth.
Is Kepler-238 d in the Habitable Zone?
Kepler-238 d orbits inside the inner edge of the habitable zone of Kepler-238. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-238: 1.065–2.511 AU (conservative: 1.349–2.380 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-238 d — one full orbit around Kepler-238 — lasts 13.2 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.115 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-238 d Discovered?
Kepler-238 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-238 d?
Kepler-238 d is 5,866.7 light-years (1,798.8 parsecs) from Earth. Light arriving here tonight left the planet about 5,867 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 103,253,920 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-238 d scores 0.21, ranking #3,741 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-238
Kepler-238
- Surface temperature
- 5,751 K (Sun: 5,772 K)
- Radius
- 1.43 R☉
The Kepler-238 Planetary System
Kepler-238 d is one of 5 known planets in the Kepler-238 system. Its siblings:
- Kepler-238 b (Super Earth)
- Kepler-238 c (Mini Neptune)
- Kepler-238 e (Neptune-like)
- Kepler-238 f (Super Earth)
Kepler-238 d — Complete Data
| Radius | 3.070 Earth radii (0.274 Jupiter radii) |
|---|---|
| Orbital period | 13.23 days |
| Orbital distance | 0.115 AU |
| Earth Similarity Index | 0.21 |
| Distance from Earth | 5,866.7 light-years (1,798.8 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-238 d
Is Kepler-238 d habitable?
No — Kepler-238 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-238 d?
Kepler-238 d is about 5,867 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 103,253,920 years to get there.
How big is Kepler-238 d compared to Earth?
Kepler-238 d has 3.07 times the radius of Earth.
How long is a year on Kepler-238 d?
One orbit around Kepler-238 takes 13.2 Earth days — short enough that 28 of its years would fit into one Earth year.
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