When Pluto has an atmosphere, it is thought to be made up of methane, nitrogen and carbon monoxide in gaseous form. This atmosphere outgases from the ice on Pluto's surface when it is closest to the sun, which warms the ... More »

Pluto has an average radius of 715 miles. The planetary body is 20 percent smaller than Earth and it has a diameter of 1,430 miles. More »

www.reference.com Science Astronomy Planets

Pluto was discovered in 1930 and is the second-largest known dwarf planet, behind Eris. It was originally considered to be the ninth planet in the solar system, but was reclassified as a dwarf planet in 2006. It is compo... More »

www.reference.com Science Astronomy

When Pluto is closest to the sun, the frozen nitrogen on its surface sublimates, meaning it turns into gas, to provide a thin atmosphere. When Pluto is farthest away from the sun, the nitrogen in its thin atmosphere refr... More »

The composition of Mars' atmosphere is 95.32 percent carbon dioxide, 2.7 percent nitrogen, 1.6 percent oxygen and 0.08 percent carbon monoxide. The remaining 0.3 percent is made up of various trace elements. More »

Mars' atmosphere is made mostly of carbon dioxide, with some nitrogen and argon. It has a very small amount of oxygen and carbon monoxide and tiny amounts of noble gases and other compounds. Earth's atmosphere is 100 tim... More »

www.reference.com Science Astronomy Planets

The planet Pluto is named after Pluto, the god of the underworld in Greek and Roman mythology. The name was suggested by a young girl, Venetia Burney Phair, in 1930 when she heard the news that a new planet had been disc... More »