The facts about Pluto’s discovery are well known: back in 1908, Percival Lowell had postulated the theory that there was another planet beyond Uranus. Lowell’s observatory had captured images of Pluto in 1915, but he did not realize it was a planet. The official discovery was made by Clyde Tombaugh on March 1930.
Facts and Figures
Pluto has a perihelion of 4.4 billion km, and an aphelion of 7.4 billion km. The mean is 5.9 billion km. The rotation is 6.4 days in a retrograde motion. Its revolution is 247.7 years. Its average distance is 39 AU. After the agreement in 2006, Pluto and its satellite Charon were classified as dwarf planets.
Surface and Geology
Its distance notwithstanding, several facts about Pluto has been established. Scientists have determined that its surface is a light brown with shades of yellow. Further analysis revealed that its main physical composition is nitrogen ice (over 98% of the surface).
There are also elements of carbon monoxide and methane detected. However, obtaining clear images of the planet are not yet possible.
Based on information provided by the Hubble Telescope, the surface is varied. There is also evidence of methane ice on the side overlooking Charon. The other side is comprised of carbon monoxide ice and more nitrogen.
Facts about Pluto’s internal structure are still nuclear. But density analysis suggests that it is made of 80% rock and the rest consisting of ice mass. The core diameter is estimated to be 1,700 km.
The major elements in the atmosphere are carbon monoxide, nitrogen and methane. The prevailing theory is that these were derived from the ice on the planet. As Pluto makes its long orbit around the Sun, it produces an anti greenhouse effect.
The result is that the planet has cooled down. The pressure is believed to be 0.3 pascal. The ethane emanates from radiolysis. More research may reveal more about the planet’s atmospheric makeup.
Several facts about Pluto’s satellites have been uncovered. Its first satellite, Charon was discovered in 1978 by James Christy. The other two (Nix and Hydra) were discovered in 2005 by the Hubble Telescope.
Charon’s orbit is such that the same side is always facing Pluto. That is, it can be seen on only side of Pluto. On the other side, it is not visible at all.
There is evidence Charon is home to cryo–geysers. Nix is almost 49,000 km away from Pluto while Hydra is 64,800 km away. Currently more research is being done to determine the physical characteristics of these satellites.
Research is also ongoing concerning the possibility that Pluto has a variable ring system. Initial data feeds from the Hubble Space Telescope do not indicate this to be the case. However, it is possible that they exist but are tenuous. These rings will also be difficult to detect if they are less than 1,000 km wide.
More facts about Pluto will emerge when the New Horizons spacecraft approaches the planet in 2015. With its arrival, more information regarding the physical appearance of the planet will be uncovered.