Wow, today on Pluto (which is incidentally quite a long time) any life which may or may not exist will have to start getting used to no longer living on the 9th planet in the Solar System. Thanks to the discovery of "2003 UB313" (catchy title, that - see the picture below for an even snazzier look), it has now been relegated to a mere "dwarf planet" by the International Astronomical Union (IAU).

So all that stuff I learnt is wrong. The BBC seems to think that textbooks will all be changed to miss off Pluto from the list of planets taught in schools.

I think this is interesting though. Has Pluto been a planet for the 76 years during which we have known of its existence? Or does the decision by these in-the-know astronomers mean that we were wrong about it all along? Who are we to judge? Who are they to judge?

Pluto is used in astrology too - will this reference be removed or its significance on our predicted moods be downgraded? Interestingly, the dictionary definition of planet talks of "a celestial body, in orbit around the Sun or another star, which has too small a mass to become a star itself, and shines by reflecting light from the star around which it revolves". I suppose that the IAU's definition was a little more stringent. It does raise an interesting question though: is this a scietific question, or a language one?

What is nice, is that the word planet actually comes from the Greek word planetes, which means "wanderer".