All entries for Saturday 26 August 2006
August 26, 2006
Writing about web page http://news.bbc.co.uk/1/hi/world/5282440.stm
…well, nothing actually; Pluto's not a planet anymore.
Apparently, after discovering a random block of ice in the Kupier Belt (think Asteroid Belt, but ice and out past Pluto – which is still there, of course, it's just not a planet) that was bigger than Pluto, Scientists decided that the definition of a planet needed tighteing. So, for something to be classed as a planet:
- it must be in orbit around the Sun
- it must be large enough that it takes on a nearly round shape
- it has cleared its orbit of other objects
Since Pluto's orbit crosses Neptune's, it therefore doesn't fulfil these criteria…
So, remember: There are only 8 planets in the Solar System.
It's not a very suprising decision, really; some moons are bigger than Pluto…