THE HISTORY OF PLUTO

How it all happened…

PLUTO

Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System (after Eris) and the tenth-most-massive body observed directly orbiting the Sun. Originally classified as the ninth planet from the Sun, Pluto was recategorized as a dwarf planet and plutoid due to the discovery that it is only one of several large bodies within the Kuiper belt.

Before 1930 (when Pluto was discovered) there were only 8 planets known. But the great astronomer Percival Lowell was absolutely convinced that somewhere beyond Neptune there was an undiscovered ninth planet, dubbed Planet X.

Lowell was sure that the Planet X would be a massive gasball (because it influenced the orbits of Uranus and Neptune). Unfortunately, he died in 1916 exhausted by his search. In 1930 a young man Clyde Tombaugh spotted Pluto. He saw that the new planet was nothing like the massive gasball. But it was the first American-discovered planet, and no one was going to be distracted by the thought that it was really just a distant icy dot.

The distant, ice-covered world is no longer a true planet, according to a new definition of the term voted on by scientists in 2006.

"Whoa! Pluto's dead," said astronomer Mike Brown, of the California Institute of Technology in Pasadena, as he watched a Webcast of the vote. "There are finally, officially, eight planets in the solar system."

Pluto is no longer a planet

What is a planet today?

According to the new definition, a full-fledged planet is an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit.

Pluto has been demoted because it does not dominate its neighborhood. Charon, its large "moon," is only about half the size of Pluto, while all the true planets are far larger than their moons.

Unique image taken by Hubble telescope where Pluto and its moon Charon are seen.

On September 13, 2006, the IAU (International Astronomical Union) included Pluto in their Minor Planet Catalogue, giving it the official minor planet designation.

REACTION

Reception to the IAU decision was mixed. While some accepted the reclassification, others seek to overturn the decision with online petitions urging the IAU to consider reinstatement.

Some members of the public have also rejected the change, citing the disagreement within the scientific community on the issue, or for sentimental reasons, maintaining that they have always known Pluto as a planet and will continue to do so regardless of the IAU decision.

CREDITS:

This presentation was made with the help of:

Wikipedia the Free Encyclopedia news.nationalgeographic.com Pluto not a planet, Astronomers rule

by Mason Inman Bill Bryson A short history of nearly

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