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Why is Pluto Not a Planet?

On February 18, 1930, Pluto was discovered by Clyde W. Tombaugh. Pluto, which was once the ninth planet, but did not meet the requirements in order to be a planet. In 2006, the International Astronomical Union declared Pluto no longer a planet. As of August 2021, there are five dwarf planets in our galaxy: Pluto, Makemake, Haumea, Ceres, and Eris. Pluto orbits the Sun despite having an orbit time of 248 years, it has moons and is a round shape, so why is it not a planet?



The history of Pluto


Pluto was officially discovered in Arizona at the Lowell Observatory in Flagstaff. Percival Lowell noticed a wobble in the orbit of Uranus and Neptune and thought it was caused by a gravitational pull of the now known Pluto. Unfortunately, for more than a decade, Lowell was unsuccessful in his findings of the mysterious object in space. Before Pluto was given its name on March 24, 1930, astronomers referred to the planet as Planet X. Officially, Tombaugh visually saw the planet using his telescope with the help of other astronomers confirming the findings. A little after Pluto was discovered, people started to question if Pluto was actually a planet.


What are the requirements to be considered a planet?


There are three criteria a celestial object has to meet to be considered a planet: orbits around the Sun, has sufficient mass, so it assumes a hydrostatic equilibrium and has cleared the neighborhood around its orbit. However, Pluto only meets two out of the three requirements. Pluto is round and does orbit around the Sun but does not clear its surroundings. Pluto has not become gravitationally dominant, meaning that it overlaps the orbits of Neptune. Therefore, Pluto not filling three out of three criteria makes Pluto a dwarf planet.


Can humans live on Pluto?


Simple answer, no, it is impossible to live on Pluto for multiple reasons. Pluto, on average 39.5 astronomical units away from the Sun and 29.6 astronomical units away from its closest point, meaning it does not receive the sunlight and heat from the Sun, unlike Earth. The atmosphere of Pluto would constantly be changing every day, it is freezing and has a low air pressure. Pluto can be as cold as -400F, humans will die from hypothermia the second they land on the surface of Pluto. The atmosphere of Pluto is unlivable as it contains gasses such as nitrogen, methane, and carbon monoxide, all toxic in large quantities. Water is a necessity, and considering water will freeze to ice, it is impossible to fuel the body without the natural resources.

 

Written by: Amber Truong

 

Sources:

Station, S. R. (2019, November 19). Why is Pluto no longer a planet? The Library of Congress. https://www.loc.gov/everyday-mysteries/item/why-is-pluto-no-longer-a-planet/

Whitbourne, K. K. P. J. (2021, May 20). Why Is Pluto No Longer Considered a Planet? HowStuffWorks. https://science.howstuffworks.com/pluto-planet.htm#:%7E:text=Pluto%20is%20not%20a%20planet,t%20cleared%20its%20neighboring%20region.

(2015, December 23). Is There Life on Pluto? Universe Today. https://www.universetoday.com/14315/is-there-life-on-pluto/#:%7E:text=As%20such%2C%20there%20is%20simply,no%20known%20organism%20could%20survive.


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