xena vs. pluto

[Cue Ms Snazzles' world-famous impersonation of the Xena Warrior-Princess Battle-Cry.]

Object 2003 UB313 is a "rock" with a surface of frozen methane and nitrogen snow, and an average temperature of -248°C. It rotates around the sun in an elliptical orbit, at its furthest point finding itself twice as far from the sun as Pluto. An article published in the most recent edition of Nature magazine, has revealed UB313 (nicknamed Xena, while its single moon is dubbed Gabrielle) is around 3,000km wide - dwarfing Pluto's diametre of 2,300km.

But here's the rub: is it a planet, or not? We all know scientists can be an amusingly adolescent bunch when it comes to their disagreements, and astronomers seem to be among the worst of the lot. Supporters of Pluto's planet-status have been pulling faces and saying "Nyah! It's SOOO not a planet! It's only a friggin Kuiper Belt Object!" However the discoverers of Xena were quick to retort: "I know you are, but what am I?!"

The problem is that Pluto and newly-discovered Xena are in fact both uncommonly large Kuiper Belt Objects. These chunks of icy debris from the Solar System's explosive origins number in the hunderds-of-thousands, slowly orbiting the sun at enormous distances. Pluto, in fact, displays some profoundly un-planet-like behaviours: its orbit is tilted at 17° from the plane of all the other planets, and is also absurdly elliptical - Pluto slips closer to the sun than Neptune for decades at a time, before again becoming the most distant "planet".

So Plutophiles are in something of a quandary. They don't want their beloved space-rock's status as "furthest outpost of the Solar System" to be taken away by haughty Xena. Yet, if Xena is denied planetary status, then what claim can Pluto have to that title, since it and Xena are essentially the same kind of entity? Meanwhile, if Xena is acknowledged as a planet, where do we draw the line? How many of these Kuiper Belt Objects can be considered planets, and who misses out?

We shall all be waiting with baited breath, for the verdict of the International Astronomical Union on UB313's status. Unfortunately, if they are declared a planet/moon system, Xena and Gabrielle will be renamed. All planets identified by the IAU are given names from Classical Mythology - and I don't think TV Mythology is allowed, alas.