Kepler-16 b

Kepler-16 b

Planet· orbits the Sun

Kepler-16 b ('Tatooine') — a Saturn-size, Saturn-mass gas giant (~0.33 Jupiter masses, 0.75 Jupiter radii) that orbits BOTH stars of the Kepler-16 binary every 229 days on a wide, stable circumbinary orbit. Because it transits both stars with a measured mass, its density is real. From its cloud tops the two suns would rise and set together — a real two-sunset world. Never imaged directly.

Open in 3D viewSee Kepler-16 b in the live, interactive 3D map

Key facts

Mass
6.32 × 10²⁶ kg
0.333 M♃ (106 M⊕)
Radius
53,830 km
8.45× wider than Earth
Surface gravity
14.6 m/s²
1.48× Earth's
Year
229 Earth days
Distance from Kepler-16 A
0.705 AU

Science

Physical

Mass
6.32 × 10²⁶ kg · 0.333 M♃ (106 M⊕)
Radius
53,830 km · 8.45× wider than Earth
Density
967 kg/m³ · 0.97× water
Surface gravity
14.6 m/s² · 1.48× Earth's
Escape velocity
39.6 km/s · 3.54× Earth's

Orbital

Semi-major axis
0.705 AU
Eccentricity
0.0069
Inclination
0.00 °
Orbital period
228.8 days
Perihelion
0.7 AU
Aphelion
0.71 AU
Mean orbital velocity
33.5 km/s

Composition

Bulk composition
A Saturn-size, Saturn-mass gas giant (~0.33 Jupiter masses, 0.75 Jupiter radii) — hydrogen and helium with a real, measured density, because it both transits and has a dynamical mass. Its remarkable feature is its orbit: it circles BOTH stars of the Kepler-16 binary every 229 days, a stable circumbinary path, so from its cloud tops two suns would rise and set together. Never imaged.
Cloud appearance
Appearance based on NASA/JPL-Caltech's artist's concept. No spacecraft has imaged this world, so its real appearance is unknown — The banded clouds shown are a representation of its class, shown only in Vision mode; Realism shows a plain spectral colour.

Radiation & temperature

Insolation
0.299 S⊕ · 30% of the sunlight Earth receives
Equilibrium temperature
188 K (-85 °C)

Discovery & history

Method
Transit detection
Name
Designated 'b' under the IAU planet-lettering convention; nicknamed 'Tatooine' (not an IAU name) for the double-sun world of Star Wars.

Announced in 2011 as the first unambiguous circumbinary planet — a world orbiting two stars at once. Its discovery, by watching it transit both suns, settled a long question about whether such planets could exist and remain stable; the press immediately named it 'Tatooine' after the two-sun world of Star Wars.

Images

Artist's concept of Kepler-16 b, the first planet found to orbit two suns — a real 'Tatooine', with a genuine double sunset. An artist's impression, not a photograph.
NASA / JPL-Caltech / T. Pyle (public domain) · Wikimedia Commons

Images from open archives · credit shown per image