Discovered in 1930, Pluto is the second closest dwarf planet to the Sun and was at one point classified as the ninth planet. Pluto is also the second most massive dwarf planet with Eris being the most massive.
Fast Facts about Pluto
1. Pluto was discovered on February 18th, 1930 by the Lowell Observatory, for the 76 years between Pluto being discovered and the time it was reclassified as a dwarf planet it completed under a third of its orbit around the Sun.
2. Clyde W. Tombaugh is the discoverer of Pluto.
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3. Pluto is named after the Greek god of the underworld, this is a later name for the more well known Hades and was proposed by Venetia Burney an eleven year old schoolgirl from Oxford, England.
4. Pluto’s orbital period is 248 Earth years. That is, It take 248 years to orbit the Sun.
5. Pluto is unlike the other planets in the Solar system. The first eight planets orbit the Sun in a path which they have cleared of other objects. Pluto, however, orbits the sun in a zone which is full of other objects that often pass between Pluto and the Sun.
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6. The first eight planets orbit the Sun while keeping the same distance from the Sun. The Earth is always 93 million miles, one Astronomical Unit, from the Sun. Pluto, however, orbits in an ellipse, an oval shape which means its distance from the Sun varies.
7. Pluto is one third water, this is in the form of water ice which is more than 3 times as much water as in all the Earth’s oceans, the remaining two thirds are rock.
8. Pluto is probably even smaller than Mercury, with a diameter of around 1400 miles (about 2240 kilometres).
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9. Pluto has five known moons, they are Charon (discovered in 1978,), Hydra and Nix (both discovered in 2005), Kerberos (discovered 2011) and Styx (discovered 2012).
10. Pluto sometimes has an atmosphere, during Pluto’s elliptical when Pluto is closer to the Sun its surface ice thaws and forms a thin atmosphere primarily of nitrogen with a little methane and carbon monoxide. When Pluto travels away from the Sun the atmosphere then freezes back to its solid state.
