Pluto was discovered on February 18, 1930 in Lolwell Observatory by Clyde Tombaugh. It is the 9th planet in the solar system.PLuto is the most distant planet from the sun. It is one of the only planets that cannot be seen without a telescope. Pluto was discovered by using mathematics. It is aproximately 39 times as far from the sun as the earth is. Its mean distance from the sun is about 3,675,000,000 miles, which is 5,914,300,000 kilometers.
Pluto travels around the sun in an elliptical orbit. It travels around the sun once every 248 years which is compared to once a year for the eath. Pluto spins on its axis while orbiting the sun. Pluto spins around about once in about six earth days. Astronomers don't know much about Pluto's size or surface conditions because it is so far from the earth.
Astronomers have obtained more information about Pluto's diameter and mass due to the discovery of Pluto's satelite Charon in 1978.Pluto has a diameter of 4,000 miles or 6,400 kilometers. It is about half the size of the earth. Astronomers believe that the temperature on Pluto may be as low as -360 degrees fahrenheit or -218 degrees celcius. It appears to be partly covered with frozen methane gas. Pluto has little or no atmosphere. It is very doubtful that there are any forms of life.