Pluto the Dwarf Planet
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.
Pluto Dwarf Planet Profile
Mass: 13,050,000,000,000 billion kg (Pluto is much, much smaller than Earth or even our moon!)
Known Moons: 5
Moon Names: Charon, Nix, Hydra, Kerberos, and Styx
Orbit Distance: 5,874,000,000 km
Orbit Period: 246.04 Earth years
Surface Temperature: -229°C (This is really, really cold! It's colder than all the other planets.)
Discovery Date: February, 18th 1930
Discovered By: Clyde W. Tombaugh
Size Of Pluto Compared To The Earth
Facts About Pluto
Pluto is named after Pluto, the Greek god of the underworld (not the Disney character):
The planet was named by Venetia Burney, an eleven year old schoolgirl from Oxford, England, who suggested the name "Pluto" to her grandfather when he was reading the newspaper in 1930, when the planet was first reported to be a planet in our solar system.
Pluto was reclassified from a planet to a dwarf planet in 2006, because of its small size and irregular orbit pattern:
In 2006 the IAU came up with the definition of a planet as “A planet is 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 neighborhood 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 its orbit around the Sun.
Pluto has five known moons:
1) Charon (discovered in 1978)
2) Hydra (discovered in 2005)
3) Nix (discovered in 2005 at the same time as Hydra)
4) Kerberos (discovered in 2011)
5) Styx (discovered in 2012)
Pluto may be the largest dwarf planet:
Astronomers are not sure whether Pluto or Eris is larger. It's hard to tell, because both dwarf planets are very small (smaller than the USA) and incredibly far away.
Pluto is smaller than many of the moons that orbit other planets.
Pluto is smaller than there moons: Ganymede, Titan, Callisto, Lo, Europa, and Triton. It is also smaller and lighter than the Earth’s moon. Pluto has 66% of the diameter of the Earth’s moon and 18% of its mass.
Pluto has a crazy, unpredictable, tilted orbit or path that it follow around the sun:
Pluto's orbit takes it between 4.4 and 7.4 billion kilometers from the Sun. Sometimes Pluto is closer to the Sun and the Earth than Neptune is.
No spacecraft, manned or unmanned, has ever visited Pluto:
Though in July 2015 the spacecraft New Horizons, which was launched in 2006, is scheduled to fly by Pluto on its 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 its solid state.
How Pluto Got Its Name:
Venetia Katharine Douglas Burney was the daughter of Rev. Charles Fox Burney, who was a professor (teacher) at Oxford. Venetia's grandfather was was Falconer Madan, who was a librarian at the University of Oxford.
On March 14th, 1930, Venetia's grandfather, Falconer Madan, read her a newspaper story from The Times that told about the discovery of a new planet. When Venetia heard the story about the new planet, she suggested the planet be named Pluto, after the Roman God of the Underworld who was able to make himself invisible.
Venetia's grandfather sent her suggestion to his friend Herbert Hall Turner, who was an astronomer. Mr. Turner cabled his American colleagues at Lowell Observatory to share Venetia's name suggestion for the new planet. Tombaugh, the astronomer who discovered Pluto was a planet, liked Venetia's proposal, so on May 1st, 1930, the name Pluto was formally adopted for the new celestial body.
Links:
The Pluto Files -- Watch famous astronomer Neil DeGrasse Tyson discuss whether Pluto is a planet.
Brainpop (you will need to get the username and password from your teacher)
Videos: