Kepler-381 d
Kepler-381 d is a terrestrial planet orbiting Kepler-381 in the constellation Lyra. It lies about 872 light-years from Earth and was discovered in 2021 using the transit method.
How Big Is Kepler-381 d?
Kepler-381 d has a radius of 1.07 times that of Earth.
Is Kepler-381 d in the Habitable Zone?
The position of Kepler-381 d relative to the habitable zone of Kepler-381 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-381: 1.304–3.045 AU (conservative: 1.652–2.887 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-381 d — one full orbit around Kepler-381 — lasts 8.26 Earth days, shorter than Mercury's 88-day year.
How Was Kepler-381 d Discovered?
Kepler-381 d was discovered in 2021 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-381 d?
Kepler-381 d is 871.9 light-years (267.3 parsecs) from Earth. Light arriving here tonight left the planet around the year 1155. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 15,345,440 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-381 d scores 0.30, ranking #1,526 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-381
Kepler-381
- Surface temperature
- 6,152 K (Sun: 5,772 K)
- Radius
- 1.57 R☉
The Kepler-381 Planetary System
Kepler-381 d is one of 3 known planets in the Kepler-381 system. Its siblings:
- Kepler-381 b (Terrestrial)
- Kepler-381 c (Terrestrial)
Kepler-381 d — Complete Data
| Radius | 1.067 Earth radii (0.095 Jupiter radii) |
|---|---|
| Orbital period | 8.26 days |
| Earth Similarity Index | 0.30 |
| Distance from Earth | 871.9 light-years (267.3 parsecs) |
| Constellation | Lyra |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2021 |
Data: NASA Exoplanet Archive, last updated 2021-12-05. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-381 d
Is Kepler-381 d habitable?
Kepler-381 d is not known to orbit within the habitable zone of Kepler-381, and as a terrestrial planet it is an unlikely candidate for life as we know it.
How far away is Kepler-381 d?
Kepler-381 d is about 872 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 15,345,440 years to get there.
How big is Kepler-381 d compared to Earth?
Kepler-381 d has 1.07 times the radius of Earth.
How long is a year on Kepler-381 d?
One orbit around Kepler-381 takes 8.3 Earth days — short enough that 44 of its years would fit into one Earth year.
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