Pluto was discovered in 1930 by Clyde Tombaugh. Pluto was once considered the ninth planet but was demoted to a dwarf planet in 2006.
On June 22nd, 1978, an American astronomer named James Christy discovered that Pluto has a large moon and is very tiny and frosty in comparison to other planets. For this reason, scientists believe Pluto is actually not a planet at all, but a frosty planetesimal.
Frosty planetesimals were most likely formed inside the Kuiper Belt. The amount of gravity belonging to the gas giants sent most of them flying around planets. Most planetesimals were destroyed inside collisions, while some turned into moons. Other planetesimals that were tossed out formed space’s Oort Cloud.
Since Pluto is so far from the sun, it has a very long year. The amount of space between Pluto and the sun is 30 to 50 times the distance between Earth and the sun. The majority of the time, Pluto’s temperature hovers near -396 degrees Fahrenheit. The atmosphere is so cold the surface ends up becoming frozen with a coat of ice and snow. However, when Pluto gets closer to the sun, its atmosphere warms up.
Pluto is one of the most icy planetesimal out of the other 40 billion. Even though no one has visited Pluto, on July 14, 2015, the first rocket was launched to see the atmosphere of the dwarf planet. More research has shown that there is a lot more to discover about Pluto.
[Source: Children's Atlas Of The Universe]