Kepler-47 b
Kepler-47 b is a puffy low-density planet orbiting Kepler-47 in the constellation Cygnus. It lies about 3,343 light-years from Earth and was discovered in 2012 using the transit method.
How Big Is Kepler-47 b?
Kepler-47 b has a radius of 3.05 times that of Earth. Its mass is 2.1 times that of Earth, giving it a density of 0.40 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is Kepler-47 b in the Habitable Zone?
The position of Kepler-47 b relative to the habitable zone of Kepler-47 cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on Kepler-47 b — one full orbit around Kepler-47 — lasts 49.5 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.288 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.021).
How Was Kepler-47 b Discovered?
Kepler-47 b was discovered in 2012 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-47 b?
Kepler-47 b is 3,343.2 light-years (1,025.0 parsecs) from Earth. Light arriving here tonight left the planet about 3,343 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 58,840,320 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-47 b scores 0.32, ranking #1,036 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-47
Kepler-47 b is a circumbinary planet — it orbits around two stars at once, like Tatooine in Star Wars.
Kepler-47
- Mass
- 0.96 M☉
- Radius
- 0.94 R☉
The Kepler-47 Planetary System
Kepler-47 b is one of 3 known planets in the Kepler-47 system. Its siblings:
- Kepler-47 c (Neptune-like)
- Kepler-47 d (Cold Gas Giant)
Kepler-47 b — Complete Data
| Radius | 3.050 Earth radii (0.272 Jupiter radii) |
|---|---|
| Mass | 2.07 Earth masses (0.007 Jupiter masses) |
| Density | 0.40 g/cm³ (Earth: 5.51) |
| Orbital period | 49.46 days |
| Orbital distance | 0.288 AU |
| Eccentricity | 0.021 |
| Earth Similarity Index | 0.32 |
| Distance from Earth | 3,343.2 light-years (1,025.0 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2012 |
Data: NASA Exoplanet Archive, last updated 2019-04-22. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-47 b
Is Kepler-47 b habitable?
Kepler-47 b is not known to orbit within the habitable zone of Kepler-47, and as a puffy low-density planet it is an unlikely candidate for life as we know it.
How far away is Kepler-47 b?
Kepler-47 b is about 3,343 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 58,840,320 years to get there.
How big is Kepler-47 b compared to Earth?
Kepler-47 b has 3.05 times the radius of Earth and about 2.1 times its mass.
How long is a year on Kepler-47 b?
One orbit around Kepler-47 takes 49.5 Earth days.
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