Kepler-16 b
Kepler-16 b is a cold gas giant orbiting Kepler-16 in the constellation Cygnus. It lies about 245 light-years from Earth and was discovered in 2011 using the transit method. It orbits within the habitable zone of its star — the region where liquid water could exist on a planet's surface.
How Big Is Kepler-16 b?
Kepler-16 b has a radius of 8.45 times that of Earth, or 0.75 times the radius of Jupiter. Its mass is 106 times that of Earth, giving it a density of 0.96 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is Kepler-16 b in the Habitable Zone?
Kepler-16 b orbits inside the conservative habitable zone of Kepler-16 — the region where a rocky planet could sustain liquid water on its surface. This makes it one of the most interesting known exoplanets in the search for life.
Habitable zone of Kepler-16: 0.308–0.764 AU (conservative: 0.391–0.724 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-16 b — one full orbit around Kepler-16 — lasts 228.8 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.705 AU — comparable to the inner Solar System. Its orbit is nearly circular (eccentricity 0.007).
How Was Kepler-16 b Discovered?
Kepler-16 b was discovered in 2011 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-16 b?
Kepler-16 b is 244.9 light-years (75.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1782. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 4,310,240 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-16 b scores 0.30, ranking #1,362 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-16
Kepler-16 b is a circumbinary planet — it orbits around two stars at once, like Tatooine in Star Wars.
Kepler-16
- Surface temperature
- 4,450 K (Sun: 5,772 K)
- Mass
- 0.69 M☉
- Radius
- 0.65 R☉
Planetary System
Kepler-16 b is the only planet known to orbit Kepler-16 so far.
Kepler-16 b — Complete Data
| Radius | 8.449 Earth radii (0.754 Jupiter radii) |
|---|---|
| Mass | 105.83 Earth masses (0.333 Jupiter masses) |
| Density | 0.96 g/cm³ (Earth: 5.51) |
| Orbital period | 228.78 days |
| Orbital distance | 0.705 AU |
| Eccentricity | 0.007 |
| Earth Similarity Index | 0.30 |
| Distance from Earth | 244.9 light-years (75.1 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2011 |
Data: NASA Exoplanet Archive, last updated 2014-05-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-16 b
Is Kepler-16 b habitable?
Kepler-16 b orbits within the habitable zone of Kepler-16, the region where liquid water could exist on a planet's surface. It sits in the conservative habitable zone — the most promising region for habitability. Whether it is actually habitable depends on its atmosphere and composition, which remain unknown.
How far away is Kepler-16 b?
Kepler-16 b is about 245 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 4,310,240 years to get there.
How big is Kepler-16 b compared to Earth?
Kepler-16 b has 8.45 times the radius of Earth and about 106 times its mass.
How long is a year on Kepler-16 b?
One orbit around Kepler-16 takes 228.8 Earth days.
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