- The number of furlongs in a mile (eight).
- The number of players on a football team (eleven).
- The number of pounds you get for passing 'Go' in monopoly (two hundred).
- The number of planets in the solar system (nine).
You'd be wrong. The International Astronomical Union just voted a resolution through that demoted Pluto from a planet to being a 'dwarf planet'. So now there are eight 'classical planets' and at least three 'dwarf planets' which, incidentally, include Ceres, the largest asteroid from belt between Mars and Jupiter, along with Pluto and 2003 UB313 (now that one needs a catchier name).
Problem caused, of course, by the discovery that 2003 UB313, despite its disappointing name, is actually larger than Pluto. So what are you going to do? Create a tenth planet - knowing full well that there are probably more out there - or demote Pluto to a not-a-real-planet group? (Or just ignore it altogether and say Pluto is a planet because it got there first?) So it's probably the best they could do.
Still, it's tough on poor Pluto. I mean, it must be hard enough out there at the dark edge of the observable solar system, all alone except for its hanger-on moon Charon, shunned by the Voyagers and now usurped by a newcomer and demoted from being a planet. I'm told it comes in towards the sun every so often, crossing Neptune's orbit, but Neptune has so arranged its diary that the two will never meet.
Sheesh. Makes my write-up life seem perfectly bearable.