Haumea
What is Haumea?
Dwarf planets· Diameter ~1,600 km (long axis 2,100 km). The rugby ball of the Kuiper belt — a dwarf planet stretched by a 3.9-hour spin, with two moons and a thin ring, named for the Hawaiian goddess of childbirth. See its tilted, elongated orbit beyond Neptune in the orbit view.
The orbit of Haumea at this moment: https://nowsky.org/solar/orbit?fw=haumea&sp=120 — replayed live, no login.
Orbit and size
| Size | ~2,100 × 1,680 × 1,070 km |
|---|---|
| Distance | 35~51 AU |
| Year | 284 yr |
| Rotation | 3.9 h — fastest large body |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Frequently asked
- How far is Haumea from Earth?
- 35~51 AU.
- How long is a day on Haumea?
- 3.9 h — fastest large body.
- In one line, what is Haumea?
- Dwarf planets — The rugby ball of the Kuiper belt — a dwarf planet stretched by a 3.9-hour spin, with two moons and a thin ring, named for the Hawaiian goddess of childbirth.
The Haumea family, scattered by one collision
Sharing orbits near Haumea are a dozen or so small bodies whose surfaces are coated in the same crystalline water ice. With similar orbital elements and identical colours and albedos, they were identified as a "collisional family" split from one parent — the only such family confirmed beyond Neptune. Haumea's rapid spin, its two moons and its ring are explained by the same impact, which stripped away the icy mantle and set the remaining core spinning fast.
The difficulty is timing. The family's orbits are so tightly clustered that the collision must date from the early solar system, when the Kuiper belt was far more crowded than now, and how common such collisions were then has become a test for models of the belt's formation. The moons Hiʻiaka and Namaka bear the names of the Hawaiian goddess's daughters, and the ring found by stellar occultation in 2017 circles at a radius of 2,290 km with a period exactly three times Haumea's rotation.
The dwarf planet in depth
Haumea was spotted in 2004–2005 by rival teams in Spain and the United States, and after a naming dispute it took the name of the Hawaiian goddess of childbirth. It orbits the Sun at an average of 43 AU every 284 years, on a path tilted 28 degrees to the ecliptic. Its mass is close to Pluto's, but its shape could hardly be more different.
Its defining trait is a rotation period of just 3.9 hours — the fastest of any body over 1,000 km wide. Centrifugal force has stretched it into a rugby ball 2,100 km along the long axis and 1,070 km along the short one. A giant collision probably stripped most of its icy mantle, leaving a rocky core spinning fast, and the debris became its moons Hi'iaka and Namaka plus a family of objects sharing its orbit. In 2017 a stellar occultation revealed a 70-km-wide ring, the first ever found beyond Neptune.
Track Haumea in the orbit view to watch it trace a steeply tilted ellipse at roughly Pluto's distance. Its surface is coated in bright crystalline water ice, with one dark red patch that makes its brightness pulse as it spins.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.