Gonggong
Gonggong (formerly 2007 OR10) is one of the largest objects in the Kuiper belt, on a highly eccentric, steeply inclined orbit. It has a small moon, Xiangliu, whose orbit let astronomers weigh the system. No spacecraft has visited.
Key facts
Science
Physical
- Mass
- 1.75 × 10²¹ kg · 0.0238 Moon masses
- Radius
- 615 km · 10% of Earth's radius
- Density
- 1,796 kg/m³ · 1.8× water
- Surface gravity
- 0.309 m/s² · 3% of Earth's
- Escape velocity
- 616 m/s · 6% of Earth's
Orbital
- Distance from the Sun
- 89.8 AU
- Semi-major axis
- 66.9 AU
- Eccentricity
- 0.5045
- Inclination
- 53.17 °
- Orbital period
- 546.78 years
- Perihelion
- 33.1 AU
- Aphelion
- 101 AU
- Mean orbital velocity
- 3.64 km/s
Rotation
- Rotation period
- 22.40 hours
Composition
- Bulk composition
- A dark red surface showing water ice and probably methane, inferred from spectroscopy; long-term irradiation of methane produces the reddening. The rock/ice interior is unconstrained — no spacecraft has visited.
- Surface imagery
- No real surface imagery exists — this object has never been visited; color is approximate, inferred from spectroscopy.
Radiation & temperature
- Insolation
- 0.000224 S⊕ · 1/4,471 of the sunlight Earth receives
- Geometric albedo
- 0.14
- Equilibrium temperature
- 33 K (-240 °C)
Discovery & history
- Discovered
- July 17, 2007
- By
- Megan Schwamb, Mike Brown and David Rabinowitz
- Method
- Photographic plates
- Name
- Gonggong, a Chinese water god with a serpent's tail who causes floods and chaos — chosen by public vote in 2019; its moon Xiangliu is named for Gonggong's serpentine minister.
Gonggong was discovered on 17 July 2007 by Megan Schwamb, Mike Brown and David Rabinowitz at Palomar (provisional designation 2007 OR10). Brown's team first nicknamed it 'Snow White', expecting an icy, bright body — but it turned out to be one of the redder large Kuiper-belt objects. For over a decade it was the largest Solar System object without a proper name, until a 2019 public vote chose Gonggong, a Chinese water god, made official by the IAU in 2020. A moon, Xiangliu, was identified in 2016 in archival Hubble images; its orbit let astronomers measure the system's mass.
Images
Images from open archives · credit shown per image