Remembering: Pluto, The Ninth Planet

For years it was theorized that there was a ninth planet. Uranus and Neptune showed clear signs of being affected by the gravitational force of another body.

However, the search repeatedly failed to find anything. Then in 1929, astronomers at the Lowell Observatory in Arizona began to search again.

On February 18, 1930, Clyde W. Tombaugh found it, a tiny planet in a ninth orbit. He shared the location with other astronomers and they were able to confirm his find. They decided upon the name Pluto, the Roman name for the Greek of the underworld, as the planet was extremely cold.

The announcement was made to the world on March 13, 1930. For seventy-six years Pluto would reign as the ninth planet. Unfortunately, on August 24, 2006, the International Astronomical Union decided upon a new definition of what a planet is. Their new definition eliminated Pluto from being a full planet and relisted it as a dwarf planet.