Discovererdisputedno discoverer credited by the IAU[1]
About the image. Drawn as a pale icy ellipsoid with its thin ring and two small moons. Its shape and ring come from measurements made as it passed in front of a star; the surface is imagined, and the moons are drawn much closer than they really are.
Most large worlds are round. Haumea is not. It spins once every 3.9 hours, an extremely short day for a world this large, and that rapid spin has pulled it into the shape of a flattened egg: roughly 2 100 kilometres long, 1 700 wide and only 1 000 from pole to pole.
Who found it?
Haumea’s discovery is one of the stranger stories in modern astronomy. Mike Brown’s team in California found it in December 2004 in images taken earlier that year and were studying it quietly. In July 2005 a Spanish team led by José Luis Ortiz announced it first, using images from 2003. Ortiz later acknowledged that the American team’s online observing logs had been looked at from his observatory the day before the announcement, but denied any wrongdoing. The International Astronomical Union settled the matter by crediting no discoverer, but recorded the discovery site as the Spanish observatory. Brown’s team chose the name: Haumea, the Hawaiian goddess of childbirth and fertility, given in 2008.
A ring and two moons
Haumea has two moons, Hiʻiaka and Namaka, named after daughters of the goddess. Both were found in 2005. Their orbits allow Haumea to be weighed: about 4 × 10²¹ kilograms, roughly a third of Pluto’s mass.
In January 2017 Ortiz’s team watched Haumea pass in front of a star and saw that the star’s light dimmed briefly on either side. Haumea has a ring, about 70 kilometres wide and some 2 290 kilometres from its centre. It was the first ring found around an object beyond Neptune.
A shattered family
Haumea’s surface is coated in bright crystalline water ice. A group of smaller icy bodies with similar orbits and similar icy surfaces travels with it. They are thought to be fragments knocked off in an ancient collision, which may also have set Haumea spinning so fast. It was the first such collisional family found beyond Neptune.
Haumea orbits the Sun every 283 years, between about 35 and 52 AU.
How far out it would be
Haumea goes around once every 283 years, at 43.116 AU from its star. Dashed circles show Jupiter, Saturn and Neptune around the Sun, on the same scale.
Earth days passing: 0
Gallery
A smooth white world stretched into a long oval, lit from the upper left by the distant Sun, with two tiny moons nearby, an impression of the dwarf planet Haumea. AI-generated painting.A white, egg-shaped world hanging in a black sky above the grey icy ground of a small moon, an impression of Haumea seen from one of its moons. AI-generated painting.Haumea, 3D artist's impression, rendered from the interactive model.Haumea, 3D artist's impression, from another angle, rendered from the interactive model.Haumea, 3D artist's impression, close-up, rendered from the interactive model.
Timeline
2004Mike Brown's team finds Haumea in December.
2005José Luis Ortiz's team announces it first; both moons are found.
2008Named after the Hawaiian goddess Haumea.
2017A ring is found during a stellar occultation.
Questions people ask
Why is Haumea egg-shaped?
It spins once every 3.9 hours, which stretches it into an elongated shape.
Who discovered Haumea?
Officially nobody. The discovery was disputed between American and Spanish teams, and the IAU credited no discoverer.