When is a planet not a planet? When it's a warrior princess. On 29 July, astronomers at Caltech's Palomar Observatory announced the discovery of an object larger than Pluto in the outer reaches of the Solar System. It's currently known only as 2003 UB313, because it was first seen - or, rather, 'the data from which the object was discovered were obtained', as one of its discoverers, Michael Brown, carefully puts it - in the second half of October 2003 (the 21st fortnight of the year; U is the 21st letter of the alphabet). Brown and his colleagues, Chad Trujillo and David Rabinowitz, have submitted a name to the International Astronomical Union, but it will remain secret until it gets the IAU's stamp of approval. Unofficially, they're calling it 'Xena', after the character played by Lucy Lawless in the camp fantasy adventure Xena: Warrior Princess that ran on TV in the late 1990s.

LRB 18 August 2005 | PDF Download