Gonggong
What is Gonggong?
Dwarf planets· Diameter 1,230 km. A dwarf planet thought to be the fifth-largest known body beyond Neptune. It is unusually red, has a moon named Xiangliu, and follows a long orbit that takes 554 years.
Orbit and size
| Diameter | ~1,230 km |
|---|---|
| Distance | 34~101 AU |
| Year | 554 yr |
| Note | very red surface; moon Xiangliu |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Gonggong, the water god who tilted the sky, and his nine-headed serpent
In Chinese myth Gonggong is the god who rules the waters. After losing a battle to the fire god Zhurong, he angrily rammed his head into Mount Buzhou, the pillar that held up the sky. The sky tilted toward the north-west and the land sank toward the south-east. The story explains why China's rivers flow east and why the stars set in the west.
The moon Xiangliu is named from the same myth: a nine-headed serpent that served Gonggong and fouled the waters wherever it went. The real Xiangliu is about 100 km across and circles Gonggong every 25 days. It was found by re-examining Hubble Space Telescope images taken in 2010 and was announced in 2016. Thanks to this moon, Gonggong's mass could be measured.
For a while Gonggong's size was badly overestimated. A 2016 study suggested it was more than 1,500 km across. Later, the moon's orbit showed that we see Gonggong almost pole-on, looking straight at one end of its spin axis. Taking this into account, the size was recalculated at about 1,230 km. Brown had expected a bright, icy body and nicknamed it Snow White, but it turned out to be very red.
The dwarf planet in depth
Gonggong was discovered in July 2007 by Megan Schwamb, Michael Brown and David Rabinowitz at Palomar Observatory in the United States. For years it had no name, only the label 2007 OR10. In 2019 a public vote chose its name, which became official in February 2020. Gonggong is a water god in Chinese myth who caused a great flood.
It is about 1,230 km across. Its long orbit brings it as close as 34 AU to the Sun and as far as 101 AU, and one lap takes 554 years. It was last at its closest point in 1857. It is now about 90 AU away and will keep moving outward until it reaches its farthest point in the 2130s. It moves in step with Neptune, going around three times for every ten Neptune orbits.
Its surface is one of the reddest among known Kuiper belt objects. The colour probably comes from ices such as methane that have been changed into reddish material by long exposure to sunlight and particles from space. Traces of water ice have also been found. It spins once in about 22 hours, slow for such a body; the pull of its moon Xiangliu may have slowed it, but this is not confirmed.
Frequently asked
- How big is Gonggong?
- The diameter of Gonggong is ~1,230 km.
- How far is Gonggong from Earth?
- The distance of Gonggong is 34~101 AU.
- What is notable about Gonggong?
- The note of Gonggong is very red surface; moon Xiangliu.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.