Kepler-821 b
Kepler-821 b is a super-Earth orbiting Kepler-821 in the constellation Lyra. It lies about 2,005 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is Kepler-821 b?
Kepler-821 b has a radius of 1.31 times that of Earth.
Is Kepler-821 b in the Habitable Zone?
The position of Kepler-821 b relative to the habitable zone of Kepler-821 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-821: 0.501–1.202 AU (conservative: 0.635–1.140 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-821 b — one full orbit around Kepler-821 — lasts just 46.1 hours, shorter than Mercury's 88-day year.
How Was Kepler-821 b Discovered?
Kepler-821 b 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-821 b?
Kepler-821 b is 2,004.5 light-years (614.6 parsecs) from Earth. Light arriving here tonight left the planet about 2,005 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 35,279,200 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-821 b scores 0.29, ranking #1,881 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-821
Kepler-821
- Surface temperature
- 5,191 K (Sun: 5,772 K)
- Mass
- 0.84 M☉
- Radius
- 0.80 R☉
- Age
- 4.8 billion years (Sun: 4.6)
Planetary System
Kepler-821 b is the only planet known to orbit Kepler-821 so far.
Kepler-821 b — Complete Data
| Radius | 1.310 Earth radii (0.117 Jupiter radii) |
|---|---|
| Orbital period | 1.92 days |
| Earth Similarity Index | 0.29 |
| Distance from Earth | 2,004.5 light-years (614.6 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-821 b
Is Kepler-821 b habitable?
Kepler-821 b is not known to orbit within the habitable zone of Kepler-821, and as a super-Earth it is an unlikely candidate for life as we know it.
How far away is Kepler-821 b?
Kepler-821 b is about 2,005 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 35,279,200 years to get there.
How big is Kepler-821 b compared to Earth?
Kepler-821 b has 1.31 times the radius of Earth.
How long is a year on Kepler-821 b?
One orbit around Kepler-821 takes 1.9 Earth days — short enough that 190 of its years would fit into one Earth year.
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