Kepler-557 b
Kepler-557 b is a mini-Neptune orbiting Kepler-557 in the constellation Cygnus. It lies about 6,840 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is Kepler-557 b?
Kepler-557 b has a radius of 2.67 times that of Earth.
Is Kepler-557 b in the Habitable Zone?
The position of Kepler-557 b relative to the habitable zone of Kepler-557 cannot be precisely determined from the available orbital data.
Habitable zone of Kepler-557: 0.943–2.207 AU (conservative: 1.195–2.092 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-557 b — one full orbit around Kepler-557 — lasts 3.71 Earth days, shorter than Mercury's 88-day year.
How Was Kepler-557 b Discovered?
Kepler-557 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-557 b?
Kepler-557 b is 6,839.9 light-years (2,097.1 parsecs) from Earth. Light arriving here tonight left the planet about 6,840 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 120,382,240 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-557 b scores 0.22, ranking #3,600 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-557
Kepler-557
- Surface temperature
- 6,068 K (Sun: 5,772 K)
- Mass
- 1.11 M☉
- Radius
- 1.16 R☉
- Age
- 3.2 billion years (Sun: 4.6)
Planetary System
Kepler-557 b is the only planet known to orbit Kepler-557 so far.
Kepler-557 b — Complete Data
| Radius | 2.670 Earth radii (0.238 Jupiter radii) |
|---|---|
| Orbital period | 3.71 days |
| Earth Similarity Index | 0.22 |
| Distance from Earth | 6,839.9 light-years (2,097.1 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-557 b
Is Kepler-557 b habitable?
Kepler-557 b is not known to orbit within the habitable zone of Kepler-557, and as a mini-Neptune it is an unlikely candidate for life as we know it.
How far away is Kepler-557 b?
Kepler-557 b is about 6,840 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 120,382,240 years to get there.
How big is Kepler-557 b compared to Earth?
Kepler-557 b has 2.67 times the radius of Earth.
How long is a year on Kepler-557 b?
One orbit around Kepler-557 takes 3.7 Earth days — short enough that 99 of its years would fit into one Earth year.
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