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 largest and second most massive dwarf planet with Eris being the largest and most massive.
Pluto Dwarf Planet Profile
Mass: 13,050,000,000,000 billion kg (0.00218 x Earth)
Diameter: 2,306 km
Known Satellites: 5
Notable Satellites: Charon, Nix, Hydra, Kerberos and Styx
Orbit Distance: 5,874,000,000 km (39.26 AU)
Orbit Period: 246.04 Earth years
Surface Temperature: -229°C
Discovery Date: 18th February 1930
Discovered By: Clyde W. Tombaugh
Size Of Pluto Compared To The Earth
Facts About Pluto
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.
Pluto was reclassified from a planet to a dwarf planet in 2006:
This is when the IAU formalised the definition of a planet as “a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.”
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 it’s orbit around the Sun.
Pluto has five known moons:
They are Charon (discovered in 1978,), Hydra and Nix (both discovered in 2005), Kerberos originally P4 (discovered 2011) and Styx originally P5 (discovered 2012) official designations S/2011 (134340) 1 and S/2012 (134340) 1.
Pluto is the second largest dwarf planet:
Eris is the largest with an average diameter of 2,326km while Pluto has a diameter of 2,306km.
Pluto is smaller than a number of moons:
These are Ganymede, Titan, Callisto, Io, Europa, Triton, and Earth’s moon. Pluto has 66% of the diameter of the Earth’s moon and 18% of its mass.
Pluto has a eccentric and inclined orbit:
This takes it between 4.4 and 7.4 billion km from the Sun meaning Pluto is periodically closer to the Sun than Neptune.
No spacecraft have visited Pluto:
Though in July 2015 the spacecraft New Horizons, which was launched in 2006, is scheduled to fly by Pluto on it’s way to the Kuiper Belt.
Pluto’s location was predicted by Percival Lowell in 1915:
The prediction came from deviations he initially observed in 1905 in the orbits of Uranus and Neptune.
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 it’s solid state.
