Why Is Pluto Not a Planet Anymore

Why is Pluto not a planet anymore?  There was a controversy regarding this question. Pluto is a dwarf planet which belongs to the Kuiper belt. In the same time, Pluto is the largest body in this belt. It is consisted of ice and rock. But comparing to other Solar System planets, Pluto is rather small and you can not see it without a telescope.

Pluto was discovered in 1930. From that time, it was thought to be a planet of the Solar System. It was an official attitude until 2006. During the 1970s, a small planet was discovered within the Solar System. This was Chiron. Considering Pluto’s mass which is very low, its status as a planet was brought into question. Some time after, other objects were discovered; those were quite similar to Pluto. One of them was Eris which was considerably larger than Pluto. In 2006, the IAU (the International Astronomical Union) gave the definition of “planet”. Pluto didn’t fulfill the requirements of this definition, so it officially stopped being a planet. It was put into a new class of dwarf planets, along with others similar celestial bodies. There are still scientists who claim that Pluto should be in class of planets.

Pluto’s largest moon is Charon (discovered in 1978 by J. Christy). Nix and Hydra are two of the Pluto’s small moons that were found in 2005.  These moons are incredibly close to Pluto. The name “Pluto” came from Roman mythology and it is the name of the god of death.

Pluto is very far from Earth, so there are not many facts known about how it really looks. It is known that the Pluto is probably covered in ice and methane and has low density. The temperature on Pluto is probably around – 230 ° C.  Since the temperature is so low, it is highly unlikely that there can be any form of life on Pluto.

One Response to “Why Is Pluto Not a Planet Anymore”

  1. Laurel Kornfeld says:

    Pluto IS still a planet; it is both a planet and a Kuiper Belt Object, and the same is true for Eris. One does not preclude the other. Only four percent of the IAU voted on the controversial demotion, and most are not planetary scientists. Their decision was immediately opposed in a formal petition by hundreds of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA’s New Horizons mission to Pluto. One reason the IAU definition makes no sense is it says dwarf planets are not planets at all! That is like saying a grizzly bear is not a bear, and it is inconsistent with the use of the term “dwarf” in astronomy, where dwarf stars are still stars, and dwarf galaxies are still galaxies. Also, the IAU definition classifies objects solely by where they are while ignoring what they are. If Earth were in Pluto’s orbit, according to the IAU definition, it would not be a planet either. A definition that takes the same object and makes it a planet in one location and not a planet in another is essentially useless. Pluto is a planet because it is spherical, meaning it is large enough to be pulled into a round shape by its own gravity–a state known as hydrostatic equilibrium and characteristic of planets, not of shapeless asteroids held together by chemical bonds. These reasons are why many astronomers, lay people, and educators are either ignoring the demotion entirely or working to get it overturned.

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