Pluto use to be our solar systems ninth Planet and the farthest from the sun but now it is no longer deemed a planet because it is simply too small. It is still a planet but now it is a “Dwarf Planet” along with the asteroid Ceres and an object named UB 313 (Zena) which incidentally is larger than Pluto which is only a mere 2,360 Km or 1,467 miles in diameter and smaller than most moons.
In Prague (Czech Republic) on August 24th 2006 it was determined by the general assembly of the International Astronomical Union (IAU) in their twenty-sixth annual (August 14 -25 2006) General Assembly that Pluto is a dwarf planet in resolution 5A that they passed.
The IAU is a group of 2500 scientist from around the world and was founded in 1919 and has included some of the best minds of recent generations however as an amateur astronomer since I was in Boy Scouts I feel this is a great loss.
Now we only have 8 planets in our little solar system and Neptune is the farthest planet from the sun and all the technical books have to be rewritten dealing with astronomical fact and all the little school children have one less planet to memorize and be tested on.
The icy and rocky Pluto was the only planet to be discovered in the United States (Flagstaff, Arizona) in 1930 by Clyde Tombaugh. He named it after the Roman god of the Underworld in keeping with the tradition for naming planets. Pluto may be small but until now it was the coldest planet in our solar system at negative 287 degrees Fahrenheit.
For the record a dwarf planet is a celestial body that:
(A) Is in orbit around the sun,
(B) Has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,
(C) Has not cleared the neighborhood around its orbit, and
(D) Is not a satellite.
Sadly by these new definitions Pluto is in fact a dwarf planet.
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