Downgrading Pluto to a Dwarf Planet

The Oxford Desk Dictionary and Thesaurus defines planet as "celestial body moving in an elliptical orbit around a star." It defines Pluto as "outermost known planet of the solar system."

The new official definition of a planet, which will not include Pluto, includes several stipulations:

-- The meeting agreed that to be called a planet, a celestial body must be in orbit around a star while not itself being a star.

-- It also must be large enough in mass for its own gravity to pull it into a nearly spherical shape and have cleared the neighbourhood around its orbit.

-- The new definition -- the first time the IAU has tried to define scientifically what a planet is -- means a second category of planets called "dwarf planets", has been created. It also creates a third category known as trans-Neptunian objects.

-- There are now only eight classical planets, dwarf planets falling into a lesser category and are not considered classical planets along with Mercury, Earth, Jupiter, Saturn, Neptune, Venus, Mars and Uranus.

Students have used two mnemonic devices for years to remember the order of the planets:

1. My very educated mother just showed us nine planets
2. My very educated mother just served us nine pizzas

Now we'll have to find another one, which could get quite tricky if 53 other spacial bodies really do qualify as planets under the new definition.