Kepler-446 d
Kepler-446 d is a super-Earth orbiting the M4 star Kepler-446 in the constellation Lyra. It lies about 314 light-years from Earth and was discovered in 2015 using the transit method.
How Big Is Kepler-446 d?
Kepler-446 d has a radius of 1.35 times that of Earth.
Is Kepler-446 d in the Habitable Zone?
The position of Kepler-446 d relative to the habitable zone of Kepler-446 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-446: 0.066–0.174 AU (conservative: 0.084–0.165 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-446 d — one full orbit around Kepler-446 — lasts 5.15 Earth days, shorter than Mercury's 88-day year.
How Was Kepler-446 d Discovered?
Kepler-446 d was discovered in 2015 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-446 d?
Kepler-446 d is 314.2 light-years (96.3 parsecs) from Earth. Light arriving here tonight left the planet around the year 1712. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 5,529,920 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-446 d scores 0.59, ranking #141 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-446
Kepler-446
- Spectral type
- M4
- Surface temperature
- 3,359 K (Sun: 5,772 K)
- Mass
- 0.22 M☉
- Radius
- 0.24 R☉
The Kepler-446 Planetary System
Kepler-446 d is one of 3 known planets in the Kepler-446 system. Its siblings:
- Kepler-446 b (Super Earth)
- Kepler-446 c (Terrestrial)
Kepler-446 d — Complete Data
| Radius | 1.350 Earth radii (0.120 Jupiter radii) |
|---|---|
| Orbital period | 5.15 days |
| Earth Similarity Index | 0.59 |
| Distance from Earth | 314.2 light-years (96.3 parsecs) |
| Constellation | Lyra |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2015 |
Data: NASA Exoplanet Archive, last updated 2015-01-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-446 d
Is Kepler-446 d habitable?
Kepler-446 d is not known to orbit within the habitable zone of Kepler-446, and as a super-Earth it is an unlikely candidate for life as we know it.
How far away is Kepler-446 d?
Kepler-446 d is about 314 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 5,529,920 years to get there.
How big is Kepler-446 d compared to Earth?
Kepler-446 d has 1.35 times the radius of Earth.
How long is a year on Kepler-446 d?
One orbit around Kepler-446 takes 5.1 Earth days — short enough that 71 of its years would fit into one Earth year.
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