Kepler-521 b
Kepler-521 b is a sub-Neptune orbiting Kepler-521 in the constellation Cygnus. It lies about 2,709 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is Kepler-521 b?
Kepler-521 b has a radius of 3.18 times that of Earth.
Is Kepler-521 b in the Habitable Zone?
The position of Kepler-521 b relative to the habitable zone of Kepler-521 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-521: 1.297–3.014 AU (conservative: 1.642–2.858 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-521 b — one full orbit around Kepler-521 — lasts 22.2 Earth days, shorter than Mercury's 88-day year.
How Was Kepler-521 b Discovered?
Kepler-521 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-521 b?
Kepler-521 b is 2,709.2 light-years (830.6 parsecs) from Earth. Light arriving here tonight left the planet about 2,709 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 47,681,920 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-521 b scores 0.21, ranking #3,770 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-521
Kepler-521
- Surface temperature
- 6,406 K (Sun: 5,772 K)
- Mass
- 1.34 M☉
- Radius
- 1.46 R☉
- Age
- 1.8 billion years (Sun: 4.6)
Planetary System
Kepler-521 b is the only planet known to orbit Kepler-521 so far.
Kepler-521 b — Complete Data
| Radius | 3.180 Earth radii (0.284 Jupiter radii) |
|---|---|
| Orbital period | 22.21 days |
| Earth Similarity Index | 0.21 |
| Distance from Earth | 2,709.2 light-years (830.6 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-521 b
Is Kepler-521 b habitable?
Kepler-521 b is not known to orbit within the habitable zone of Kepler-521, and as a sub-Neptune it is an unlikely candidate for life as we know it.
How far away is Kepler-521 b?
Kepler-521 b is about 2,709 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 47,681,920 years to get there.
How big is Kepler-521 b compared to Earth?
Kepler-521 b has 3.18 times the radius of Earth.
How long is a year on Kepler-521 b?
One orbit around Kepler-521 takes 22.2 Earth days — short enough that 16 of its years would fit into one Earth year.
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