Why Pluto is not a Planet?
Pluto was discovered in 1930 by Clyde W Tombaugh. It is observed later that unlike other planets which constitute their only existence in their region, Pluto and its moons are known to be an example for collection of objects called Kuiper belt. Kuiper belt is similar to an asteroid belt. Asteroid belt generally is made up of metal and rock. But the Kuiper belt is made up of icy chunks of various substances. Kuiper belt composition is almost similar to that of comets which is a mixture of frozen water, ammonia and various hydrocarbons such as methane. Astronomers have found that there are at least 70,000 icy objects with the same composition as Pluto, that are 100 kilometers apart or more.
So according to this idea it is said that Pluto is not a planet and it is just another Kuiper belt object. And if we go further into recent discoveries, in 2005 Mike brown and his team has discovered an object farther out than the orbit of Pluto. It had the same size or even larger than that of Pluto. It is officially named as 2003UB313 and later was designated as Eris. It was found to have 25% more mass than Pluto. As Eris is larger and made of ice/rock mixture and has more mass than Pluto, the concept of nine planets has in the Solar system has started fading away. The final decision about the status of Pluto as planet was set to be discussed at the XXVI general assembly of the International Astronomical Union, held from August 14 to August 25, 2006 at Prague, Czech Republic. At last the astronomers have given the report controversially that Pluto is classified along with Eris under ‘dwarf planet,.
There is a scientific postulate that a celestial body to be called as a planet should be able to clear the neighborhood of its orbit. This is not satisfied by Pluto. Because a planet should be the dominant gravitational body in its orbit and should be able to attract all other objects in its orbit. But Pluto is only 0.07 times the mass of other objects in its orbit while the earth is 1.7 million times. So any object that does not meet this criterion will be classified as ‘dwarf planet,. So Pluto is a ‘dwarf planet,.
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