Poor, poor Pluto

Remember 2003 UB313?

Ah, I won't blame you if you don't. 2003 UB313 was the little icy rock in space that was discovered in 2003 and which was instrumental to the International Astronomical Union (IAU) to rule three years later that Pluto did not merit its historical status as a planet in our Solar System.

Instead, the IAU created a new sub-category called Dwarf Planets of which Pluto became its defacto leader. 2003 UB313, initially given the name Xena but later officially designated Eris, was also placed into this category along with countless thousands (maybe more) of other discovered and yet-to-be-discovered little rocks in our spatial neighbourhood.

The Dwarf Planets do not necessarily reside in the region of space beyond Neptune, known as the Kuiper Belt. Closer to our Earth, Ceres in the asteroid belt between Mars and Jupiter is also a member of the Dwarf Planets.

But coming back to our story, it seems that Pluto has now suffered more indignity. The latest official measurements have uncovered that Eris is, in fact, about 27 per cent larger than Pluto.

Eris is presently some 14.5 billion km from Earth. It has a highly elongated orbit around the Sun that lasts 560 years. It also has a moon, which is called Dysnomia, and scientists used this satellite, along with the Keck Observatory, Hubble Space Telescope to come to this conclusion about its mass.

So let's hail Eris as the largest of the Dwarf Planets, but spare a little thought too for poor Pluto which seems to be at the receiving end of one indignity after another.