Let's get this ball rolling...
** A forbidden planet **
When is a planet just a big rock? That's the question teasing astronomers who
are busy deciding whether the Solar System should continue to have nine planets.
The new number could range from eight to twenty.
Surprisingly perhaps, there is no agreed scientific definition of 'planet' and
there are several rival suggestions.
http://news.bbc.co.uk/1/hi/sci/tech/5099292.stm
Horizon reports on the possible downgrading of Pluto to a 'Kuiper Belt Object'.
http://www.bbc.co.uk/horizon