Pluto is the second closest dwarf planet to the Sun and from 1930 when it was discovered up until 2006, it was also considered the ninth planet of the solar system.
Pluto is the largest dwarf planet but only the second most massive, with Eris being the most massive.
The dwarf planet Pluto is named for the ancient Roman god of the underworld. In Roman mythology, Pluto was the son of Saturn who, with his three brothers, controlled the world: Jupiter controlled the sky, Neptune controlled the sea, and Pluto ruled the underworld.
It takes Pluto 246.04 Earth years to orbit the Sun.
It takes Pluto 6 days, 9 hours, and 17 minutes to spin once.
Pluto spins in the opposite direction as Earth, which means the sun rises in the west and sets in the east.
When Pluto was considered a planet, it was the coldest of all the planets. Temperatures on Pluto can range from -240°C to -218°C (-400°F to -360°F).
Pluto is smaller than many moons. When it was first discovered, Pluto’s small size surprised the scientific community who predicted it would be as large as Jupiter. The moons Ganymede, Titan, Callisto, Io, Europa, Triton, and the Earth’s moon are all larger than Pluto. It has 66% of the Moon’s diameter and just 18% of its mass.
Pluto has five known moons. These are Charon, Styx, Nix, Kerberos and Hydra. The latter two moons were known as S/2011 (134340) 1 and S/2012 (134340) 1 before they were officially named.
Because Pluto’s moon Charon and Pluto orbit each other, Charon appears to stand still in Pluto’s sky. Additionally, the same sides of Pluto and Charon always face each other.
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. Pluto’s surface is covered with ices, and has several mountain ranges, light and dark regions, and a scattering of craters.
Pluto is the only known dwarf planet with an atmosphere. It is very thin and would be toxic for humans to breathe. When Pluto is at its perihelion (closest to the sun), Pluto’s atmosphere is gas. When Pluto is at its aphelion (farthest from the sun), its atmosphere freezes and falls like snow.
Sunlight on Pluto has the same intensity as moonlight on Earth. This is because it located so far from the Sun in the outer solar system – approximately 5,945,900,000 km.
Pluto has been visited by one spacecraft. The New Horizons spacecraft, which was launched in 2006, flew by Pluto on the 14th of July 2015 and took a series of images and other measurements. New Horizons is now on its way to the Kuiper Belt to explore even more distant objects.
Some of the ashes of Clyde Tombaugh, the astronomer who discovered Pluto, are onboard the New Horizons probe that went to Pluto and beyond.
The orbit of Pluto is chaotic and unpredictable. Scientists are able to predict the location of Pluto along its orbit path for the next 10-20 million years – beyond that it is unknown.
Officially, Pluto’s name is now asteroid number 134340 after being downgraded from a planet to a dwarf planet.
In 1941, the newly created element plutonium was named after Pluto.
The Disney character Pluto, a dog, is said to have been named after the former planet.