Pluto

Charde’ Howard

March 26, 2008

Dr. Kebede

Physical Science

Pluto

In 1930, 24-year old Clyde Tombaugh, in search of a trans-neptunian planet (also known as Planet ‘X’) discovered Pluto. One night, while Tombaugh was looking through his telescope at Lowell Observatory in Arizona, he saw a faint speck jump through the stars. He finally found what he had been in search of for nearly one year, the ninth planet of our solar system, Pluto. Shortly after Pluto’s discovery there was controversy about its classification as a planet due to its size.

Pluto’s average distance from the sun is about three and half billion miles, making it the farthest planet from the sun. However, there are times that Pluto is closer to the sun than Neptune due to the path of its orbit. “Pluto’s orbital period is exactly one and a half times longer than Neptune’s” (Arnett 2006). Pluto and Neptune’s orbital paths at times seem as if they cross. Due to Pluto’s high orbital inclination they do not cross and will not collide.

Pluto’s distance from the sun explains its temperatures, which are -235 to -210C (38 to 63K). Although, its composition is unknown, its density of 2gm/cm3 indicates that it is probably a mixture that consists of 70% rock and 30% water ice. Pluto’s surface has light and bright regions. The darker regions are the warmer regions. The bright areas are the cooler areas, which are believed to be covered by ices of nitrogen with small amounts of methane, ethane and carbon monoxide. Due to Pluto’s frigid temperatures the gases on Pluto spend the majority of its long year frozen.

Pluto is the smallest of the planets. In 1978 before the discovery of Charon, Pluto’s largest moon, astronomers thought Pluto was larger than it was, because the images of Pluto and Charon were blurred together. Some view the two as a double planet, rather than a planet and a moon because they are so close in size. The composition of Charon is unknown, however, its low density indicates that its make...