In school, we memorized the 9-planets in order by remembering:
My Very Educated Mother Just Served Us Nine Pizzas: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.
Today we must say My Very Educated Mother Just Served Us NOTHING – because in August, 2006, Pluto got dumped for being ordinary. She was no longer considered a planet – just another common clump of space clutter.
For many years, astronomers predicted there would be another planet in our 8-planet solar system – they even named it “Planet X.” In 1930, Clyde W. Tombaugh, a 22-year old astronomer, was given the dull task of comparing thousands of photo images of space. Any moving object, like an asteroid, comet, or planet, would appear to jump sequentially from one photograph to the next.
It took Clyde a year to line everything up and discover the new planet. He named it ‘Pluto’ – the Roman God of the Underworld – (NOT the Disney Dog.) Then in 1978, when more sophisticated observatories began taking a closer look at the universe, it was discovered that Pluto was just one of over 70,000 icy clumps – of the same composition – in roughly the same orbit. Pluto got dumped as a planet.
Today you can still call Pluto, Pluto – but it’s not officially a planet. It’s just one more space in the cloud.
Pluto: https://www.google.com/