Why is Pluto No Longer a Planet?

For as long as I could remember, Pluto was the distant planet at the end of our solar system.

There never was a doubt in my mind that Pluto was not really a planet, but apparently it was recently debunked as an official planet.  Let’s start off by looking into some history of Pluto.

Pluto was first identified in 1930 by an astronomer that went by the name Clyde W. Tombaugh who was given the daunting task of trying to validate and discover what was at that time called Planet X.

Tombaugh had to compare plates and isolate the differences between planets and comets between the pictures.  It took him about a year before he was able to identify his discovery of Planet X and validate it.

After discovery, the name was chosen by a child in Oxford England and since then the Planet X would forever be called Pluto…or so we thought.  The identifying and naming of Pluto completed our solar system as having 9 district planets.

In 1978, astronomers where finally able to determine the planets mass by discovering its largest moon in orbit called Charon.  Pluto came in at a whopping 1500 miles in diameter, truly the smallest planet in the solar system!

With the advancement of technology came powerful observatories both on the ground and in space.  These observatories helped to change how we see outer space and more specifically our Solar System.

This new technology is the very thing that caused the deplaneting of Pluto and discovery of a bunch of orbiting objects known as the Kuiper Belt.  These frozen space objects, about 70K in total, are all very similar to Pluto and float out as an extension of the Neptune.  The discovery of these space objects is what classified Pluto as part of the Kuiper Belt instead of an actual planet.

As astronomers continued to identify large objects in the Kuiper Belt, none where quite the size of Pluto, until 2005 when a discovery was made it was an object with more mass than Pluto called Eris.

The eye opening event led the astronomers to vote and decide the definitions of what a planet is and hence the name dwarf planet was created.  Both Pluto and Eris fall into the category of a dwarf planet.

To this day there are still discussions on whether demoting Pluto was the right thing to do.

As with all things science, evolving and redefining is a way of life and the same goes for astronomy!

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