Kepler-16 b

Planet· orbits Kepler-16 A

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 gravity

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; Computed from mass and radius
Surface gravity: 14.6 m/s² · 1.48× Earth's gravity; Computed from mass and radius
Escape velocity: 39.6 km/s · 3.54× Earth's escape velocity; Computed from mass and radius

Orbital

Semi-major axis: 0.705 AU; NASA Exoplanet Archive + Doyle et al. 2011 (eclipsing-binary + transit solution)
Eccentricity: 0.0069; NASA Exoplanet Archive + Doyle et al. 2011 (eclipsing-binary + transit solution)
Inclination: 0.00 °; NASA Exoplanet Archive + Doyle et al. 2011 (eclipsing-binary + transit solution)
Orbital period: 228.8 days; NASA Exoplanet Archive + Doyle et al. 2011 (eclipsing-binary + transit solution)
Perihelion: 0.7 AU; Computed from the orbital elements
Aphelion: 0.71 AU; Computed from the orbital elements
Mean orbital velocity: 33.5 km/s; Computed from the orbital elements

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 Visual mode; Realism shows a plain spectral colour.

Radiation & temperature

Insolation: 0.299 S⊕ · 30% of the sunlight Earth receives; Computed from Kepler-16 A's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
Equilibrium temperature: 188 K (-85 °C); Computed model value for its ~0.7 AU orbit around the combined light of both stars — not measured.

Discovery & history

Discovered: September 15, 2011
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