Discovered in 2004 in an orbit that ranges between 34 and 51 astronomical units from the Sun, Haumea is one of the largest Kuiper Belt Objects and also one of the oddest.

Haumea has two moons, a mass about a third of Pluto’s and a strange elongated shape. It rotates every 3.9 hours making it the most rapidly spinning object of its size in the Solar System, probably as a result of a collision in the distant past.

But here’s the oddity. Unlike all other large Kuiper Belt Objects, which are covered in methane ice and so slightly red in colour, Haumea and its two moons are covered in water ice, giving them a blue tinge. Moreover, Haumea is much denser than water and so must have a rich rocky core. Haumea must be profoundly different to other big Kuiper Belt Objects.

Today the story gets even stranger. Pedro Lacerda at Queen’s University in Belfast says he has spotted a dark red spot on the surface of Haumea using a 2.2 metre telescope at the University of Hawaii, the first time that surface detail has been been made out on such a body (if you exclude Pluto, of course). The question is how did it get there and what is it made of.

Lacerda rules out the possibility that the spot is a mountain or valley because that would change the brightness in an easily identifiable way. Instead he speculates on two possibilities. The first is that the spot could be a region on Haumea where the interior is trickling out. Whatever that stuff might be, it is likely to be warmer and therefore redder than water ice. His second idea is that the spot could be the site of a recent impact of a smaller Kuiper Belt Object, most of which are believed to be covered by a red organic materials.

Either way, that’s interesting news. The Kuiper Belt was discovered only in 1992 and his since revolutionised our understanding of the Solar System and how it formed. Clearly there’s a lot more we can learn from these mysterious objects

Ref: arxiv.org/abs/0911.0009: The Dark Red Spot on KBO Haumea