Haumea

Haumea

Dwarf Planet· orbits the Sun

Haumea is a dwarf planet in the Kuiper belt spun into an egg shape by a ≈3.9-hour rotation, one of the fastest of any large body. It has two moons and a thin ring. No spacecraft has visited.

Open in 3D viewSee Haumea in the live, interactive 3D map

Key facts

Mass
4.01 × 10²¹ kg
0.0546 Moon masses
Radius
780 km
12% of Earth's radius
Surface gravity
0.439 m/s²
4% of Earth's
Day length
3.92 hours
Year
283 Earth years
103,270 Earth days
Distance from Sun
43.1 AU
Moons
2
Hiʻiaka & Namaka

Science

Physical

Mass
4.01 × 10²¹ kg · 0.0546 Moon masses
Mean radius
780 km · 12% of Earth's radius
Density
2,015 kg/m³ · 2× water
Surface gravity
0.439 m/s² · 4% of Earth's
Escape velocity
828 m/s · 7% of Earth's

Orbital

Distance from the Sun
49.8 AU
Semi-major axis
43.1 AU
Eccentricity
0.1941
Inclination
24.83 °
Orbital period
282.74 years
Perihelion
34.7 AU
Aphelion
51.4 AU
Mean orbital velocity
4.54 km/s

Rotation

Rotation period
3.92 hours

Composition

Bulk composition
A surface of nearly pure crystalline water ice over a predominantly rocky body, inferred from spectroscopy and its high density; the rapid spin stretches it into an ellipsoid.
Surface imagery
No real surface imagery exists — this object has never been visited; color is approximate, inferred from spectroscopy.

Radiation & temperature

Insolation
0.000539 S⊕ · 1/1,856 of the sunlight Earth receives
Geometric albedo
0.66
Equilibrium temperature
32 K (-241 °C)

Discovery & history

Discovered
December 28, 2004
By
Teams led by Mike Brown (Caltech) and José Luis Ortiz (Spain), amid a priority dispute
Method
Photographic plates
Name
The Hawaiian goddess of fertility and childbirth; its moons are named for her daughters.

Haumea was first detected on 28 December 2004 by a team led by Mike Brown at Caltech — who codenamed it 'Santa' for its Christmas-time discovery — and independently reported in 2005 by José Luis Ortiz's group in Spain from 2003 images (provisional designation 2003 EL61), sparking a lasting priority dispute. It is one of the fastest-spinning large bodies known, whirling around every ~3.9 hours into an elongated, egg-like shape, and in 2017 a stellar occultation revealed a ring — the first found around a trans-Neptunian object. It was named for Haumea, the Hawaiian goddess of fertility and childbirth; its two moons, Hiʻiaka and Namaka, are named for her daughters.

Images

Artist's impression of the elongated, fast-spinning dwarf planet Haumea — not a photograph
NASA / ESA / STScI (A. Feild) (public domain) · Wikimedia Commons

Images from open archives · credit shown per image