Towards the end of our solar system lies the smallest of all the nine planets, Pluto. In 1905, Percival Lowell, an American astronomer, found the force of gravity of some unknown planet to be affecting the orbits of Neptune and Uranus. In 1915, he predicted the location of a new planet, and began searching for it from his observatory. Lowell used a telescope to photograph the area of the sky where he thought the planet would be found. However, Lowell died without ever actually discovering Pluto. In 1930, while continuing with Lowell's work, Clyde W. Tombaugh, used predictions made by Lowell and other astronomers and photographed the sky with a more powerful telescope. Tombaugh examined the photos and found Pluto's image. Lowell and Tombaugh's work helped to find the ninth planet of our solar system, but throughout the years we have been able to discover more about the little blue planet.
             Pluto is usually the most distant planet from the sun. Pluto is about thirty-nine times as far from the sun as Earth is. Its mean distance from the sun is about three billion, six hundred sixty-six million, two hundred thousand miles. Pluto travels around the Sun in an elliptical orbit; at some point in its orbit it comes closer to the Sun than Neptune, the eighth planet of our solar system. Pluto stays inside Neptune's orbit for about twenty earth-years. This switching of planets only occurs about every two hundred forty-eight earth years, which is very close to the time it takes Pluto to orbit the Sun. Pluto last entered Neptune's orbit on January 23, 1979, and stayed there until March 15, 1999. As Pluto orbits the sun, the planet spins on its axis. A complete rotation for Pluto takes about six earth-days.
             Astronomers know little about Pluto's size or surface conditions because of its vast distance from the earth. Pluto has an estimated diameter of about one thousand, four hundred, and thirty miles, less than a fif...