Kepler-401 d
Kepler-401 d is a mini-Neptune orbiting Kepler-401 in the constellation Cygnus. It lies about 3,149 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is Kepler-401 d?
Kepler-401 d has a radius of 2.27 times that of Earth.
Is Kepler-401 d in the Habitable Zone?
The position of Kepler-401 d relative to the habitable zone of Kepler-401 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-401: 1.098–2.567 AU (conservative: 1.391–2.434 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-401 d — one full orbit around Kepler-401 — lasts 184.3 Earth days, between the years of Mercury (88 days) and Earth (365 days).
How Was Kepler-401 d Discovered?
Kepler-401 d was discovered in 2016 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-401 d?
Kepler-401 d is 3,149.2 light-years (965.6 parsecs) from Earth. Light arriving here tonight left the planet about 3,149 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 55,425,920 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-401 d scores 0.38, ranking #597 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-401
Kepler-401
- Surface temperature
- 6,117 K (Sun: 5,772 K)
- Radius
- 1.33 R☉
The Kepler-401 Planetary System
Kepler-401 d is one of 3 known planets in the Kepler-401 system. Its siblings:
- Kepler-401 b (Super Earth)
- Kepler-401 c (Mini Neptune)
Kepler-401 d — Complete Data
| Radius | 2.270 Earth radii (0.203 Jupiter radii) |
|---|---|
| Orbital period | 184.26 days |
| Earth Similarity Index | 0.38 |
| Distance from Earth | 3,149.2 light-years (965.6 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2016-05-06. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-401 d
Is Kepler-401 d habitable?
Kepler-401 d is not known to orbit within the habitable zone of Kepler-401, and as a mini-Neptune it is an unlikely candidate for life as we know it.
How far away is Kepler-401 d?
Kepler-401 d is about 3,149 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 55,425,920 years to get there.
How big is Kepler-401 d compared to Earth?
Kepler-401 d has 2.27 times the radius of Earth.
How long is a year on Kepler-401 d?
One orbit around Kepler-401 takes 184.3 Earth days.
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