It used to be a planet. Then in 2006 it was relegated and is now called 134340 Pluto. Our chief scientist looks at the story of the little (former) planet that caused a big fuss.
In 2006 there was a right hoodoo
happening up there in the Milky Way because boffins have been re-drawing the
planets and the results of their work mean that what most of us have been
taught- that there are nine planets in our solar system- is now wrong. Without
recourse to a fleet of spaceships or even a nifty destructor ray scientists
have destroyed Pluto, at least as far as its planetary status is concerned. In
late August, a new definition of a planet was approved by a seemingly
self-appointed clique of scientists with presumably nothing better to do.
It all happened at the grandly monikered
General Assembly of the International Astronomical Union (AIU) held in Prague.
424 astronomers (who knew there were even that many?) voted on the definition
after the sort of horse trading often seen at the United Nations over more
serious matters. An initial proposal by the AIU’s planet definition committee
chaired by Owen Gengerich, would have added three more planets to the roll call, perhaps assuming that Pluto’s
position was unassailable. The suggestion was based on the fact that these
bodies were the same size or larger than Pluto, one of which, the modestly
named 2003 UN313 had been hailed as “the tenth planet” due to being slightly
bigger whilst the other two new planets would have been the asteroid Ceres and
Charon, in a promotion from being one of Pluto’s moons. This proposal caused a
furore and after several days wrangling four alternative proposals were put
forward.
