I was taught in primary school that there are nine planets (Mercurcy, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto) but as time went on, I realized that they are eight. "Oops my teacher taught me the wrong thing" I taught. The next day I decided to put the question to one of my friends who he told me that the planet collided with one of the space stones and got broken into pieces...lol, that was a distanced lie from truth. But at last I know the truth and realised that my teacher wasn't wrong....This triggered me up to share more light about the planet (PLUTO)
HISTORY OF PLUTO
Pluto was discovered on Feb. 18, 1930 at the Lowell Observatory in flagstaff, Arizona by a US astronomer, Clyde W. Tombaugh with the help of William Pickering (a prolific planet predictor)
In 1906, Percival Lowell, the founder of the Lowell Observatory in flagstaff, Arizona started to a project in search for a possible ninth planet. In March 19, 1915 he and his member captured a faint image of Pluto, but they were not recognized for what they were.
Unfortunately, Lowell could not accomplish the mission before his death in 1916. Then, the job was handed to Clyde Tombaugh who later discovered the planet.
HOW PLUTO WAS DOWNGRADED FROM THE PLANET TO DWARF PLANET
On 24 August, 2016, the International Astronomical Union (IAU) adopted a resolution criteria for defining a planet. The criteria are:
The planet must be round
It must orbit around the sun
It must have "cleared the neighborhood" of its orbit
Pluto meets the first two criteria but i. e. it is round and orbits around the sun, but it's loosing out on the third, i. e. it has not been able to clear the neighbourhood.
"Clearing the neighbourhood" means it has achieved gravitational dominance. So due to the fact that Pluto has not cleared his neighbourhood, its status was immediately downgraded to that of a "DWARF PLANET".
WHAT IS DWARF PLANET?
A "dwart planet" as defined by the International Astronomical Union (IAU) is a celestial body in direct orbit of the sun that is massive enough that its shape is controlled by gravitational forces rather than mechanical forces (and is thus ellipsoid in shape), but has not cleared its neighbourhood region of other objects.
SOME FACTS ABOUT PLUTO
It has about same size of the moon
It takes about 248 Earth years for Pluto to orbit around the sun and since its discovery the planet hasn't orbit the sun. It remains about 160 years more for Pluto to orbit the sun.
It takes about 300 minutes (5hrs) for sunlight to reach the planet because of its great distance from the sun
Thanks for reading
REFERENCES: 1 - 2 - 3
If you write STEM (Science, Technology, Engineering, and Mathematics) related posts, consider joining #steemSTEM on discord here. If you are from Nigeria, you may want to include the #stemng tag in your post. You can visit this blog by 
