Kepler-398 d
Kepler-398 d is a terrestrial planet orbiting Kepler-398 in the constellation Lyra. It lies about 579 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is Kepler-398 d?
Kepler-398 d has a radius of 0.88 times that of Earth.
Is Kepler-398 d in the Habitable Zone?
The position of Kepler-398 d relative to the habitable zone of Kepler-398 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-398: 0.296–0.733 AU (conservative: 0.376–0.695 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-398 d — one full orbit around Kepler-398 — lasts 6.83 Earth days, shorter than Mercury's 88-day year.
How Was Kepler-398 d Discovered?
Kepler-398 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-398 d?
Kepler-398 d is 578.5 light-years (177.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1448. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 10,181,600 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-398 d scores 0.33, ranking #961 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-398
Kepler-398
- Surface temperature
- 4,493 K (Sun: 5,772 K)
- Radius
- 0.61 R☉
The Kepler-398 Planetary System
Kepler-398 d is one of 3 known planets in the Kepler-398 system. Its siblings:
- Kepler-398 b (Terrestrial)
- Kepler-398 c (Terrestrial)
Kepler-398 d — Complete Data
| Radius | 0.880 Earth radii (0.079 Jupiter radii) |
|---|---|
| Orbital period | 6.83 days |
| Earth Similarity Index | 0.33 |
| Distance from Earth | 578.5 light-years (177.4 parsecs) |
| Constellation | Lyra |
| 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-398 d
Is Kepler-398 d habitable?
Kepler-398 d is not known to orbit within the habitable zone of Kepler-398, and as a terrestrial planet it is an unlikely candidate for life as we know it.
How far away is Kepler-398 d?
Kepler-398 d is about 579 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 10,181,600 years to get there.
How big is Kepler-398 d compared to Earth?
Kepler-398 d has 0.88 times the radius of Earth.
How long is a year on Kepler-398 d?
One orbit around Kepler-398 takes 6.8 Earth days — short enough that 53 of its years would fit into one Earth year.
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