Haumea

The fast rotating dwarf planet, Haumea (artist's impression)
Credit: Stephanie Hoover

​Haumea (pronounced how-may-a) is a dwarf planet. It was discovered in 2004 and officially became a dwarf planet in 2008. Haumea completes one orbit of the Sun every 283 Earth years. 

​Haumea is part of the Kuiper Belt. It orbits the Sun from a distance of about 43 astronomical units (AU). However, it is sometimes as close as 35 AU or as far out as 52 AU. This is because its orbit has a very elliptical shape.

We have not yet been able to look at Haumea in any detail. This is because it is too far away and too small to be clearly seen using a telescope on Earth. Also, spacecraft have not visited it yet. However, astronomers think it looks like a rugby ball. They worked this out by observing the way it reflects light. Haumea has this unusual shape because it is one of the fastest rotating objects in our Solar System. It spins once every 4 hours!

Like Makemake, Haumea is smaller than Eris or Pluto. Its longest side is about 2000 km in size. The shorter side is about 1000 km. Haumea contains about one-quarter of their mass of Pluto. Haumea is made of rock covered in ice. It is very cold because it is so far from the Sun. The average surface temperature is thought to be around -240 °C (or 32 K).

Haumea has two known moons, named Hiʻiaka and Namaka. It is also the first known object in the Kuiper Belt to have rings.