HomeAboutLogin
       
       
 

   
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of icy trans-Neptunian objects. It was the first such object to be discovered. It is the largest and second-most massive known dwarf planet in the Solar System and the ninth-largest and tenth-most-massive known object directly orbiting the Sun. It is the largest known trans-Neptunian object by volume but is less massive than Eris, a dwarf planet in the scattered disc. Like other Kuiper belt objects, Pluto is primarily made of ice and rock and is relatively small—about one-sixth the mass of the Moon and one-third its volume. It has a moderately eccentric and inclined orbit during which it ranges from 30 to 49 astronomical units (4.4–7.3 billion km) from the Sun. This means that Pluto periodically comes closer to the Sun than Neptune, but a stable orbital resonance with Neptune prevents them from colliding. In 2014, Pluto was 32.6 AU from the Sun. Light from the Sun takes about 5.5 hours to reach Pluto at its average distance (39.4 AU).

Pluto was discovered in 1930 by Clyde Tombaugh, and was originally considered the ninth planet from the Sun. After 1992, its status as a planet fell into question following the discovery of several objects of similar size in the Kuiper belt. In 2005, Eris, which is 27% more massive than Pluto, was discovered, which led the International Astronomical Union (IAU) to define the term "planet" formally for the first time the following year. This definition excluded Pluto and reclassified it as a member of the new "dwarf planet" category (and specifically as a plutoid). Some astronomers believe Pluto should still be considered a planet.

Pluto has five known moons: Charon (the largest, with a diameter just over half that of Pluto), Styx, Nix, Kerberos, and Hydra. Pluto and Charon are sometimes considered a binary system because the barycenter of their orbits does not lie within either body. The IAU has not formalized a definition for binary dwarf planets, and Charon is officially classified as a moon of Pluto.

On 14 July 2015, the New Horizons spacecraft became the first spacecraft to flyby Pluto. On its brief flyby, New Horizons made detailed measurements and observations of Pluto, and its moons.

More on this Website

 
 
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of icy trans-Neptunian objects. It was the first such object to be discovered. It is the largest and second-most massive known dwarf planet in the Solar System and the ninth-largest and tenth-most-massive known object directly orbiting the Sun. It is the largest known trans-Neptunian object by volume but is less massive than Eris, a dwarf planet in the scattered disc. Like other Kuiper belt objects, Pluto is primarily made of ice and rock and is relatively small—about one-sixth the mass of the Moon and one-third its volume. It has a moderately eccentric and inclined orbit during which it ranges from 30 to 49 astronomical units (4.4–7.3 billion km) from the Sun. This means that Pluto periodically comes closer to the Sun than Neptune, but a stable orbital resonance with Neptune prevents them from colliding. In 2014, Pluto was 32.6 AU from the Sun. Light from the Sun takes about 5.5 hours to reach Pluto at its average distance (39.4 AU).

Pluto was discovered in 1930 by Clyde Tombaugh, and was originally considered the ninth planet from the Sun. After 1992, its status as a planet fell into question following the discovery of several objects of similar size in the Kuiper belt. In 2005, Eris, which is 27% more massive than Pluto, was discovered, which led the International Astronomical Union (IAU) to define the term "planet" formally for the first time the following year. This definition excluded Pluto and reclassified it as a member of the new "dwarf planet" category (and specifically as a plutoid). Some astronomers believe Pluto should still be considered a planet.

Pluto has five known moons: Charon (the largest, with a diameter just over half that of Pluto), Styx, Nix, Kerberos, and Hydra. Pluto and Charon are sometimes considered a binary system because the barycenter of their orbits does not lie within either body. The IAU has not formalized a definition for binary dwarf planets, and Charon is officially classified as a moon of Pluto.

On 14 July 2015, the New Horizons spacecraft became the first spacecraft to flyby Pluto. On its brief flyby, New Horizons made detailed measurements and observations of Pluto, and its moons. More...

 
    The Universe
  The Universe
The Universe is all of time and space and its contents. The Universe includes planets, stars, galaxies, the contents of intergalactic space, the smallest subatomic particles, and all matter and energy. The majority of matter and energy is most likely...
 
    The Nine Planets
  The Nine Planets
The Nine Planets is an overview of the history, mythology, and current scientific knowledge of each planet and the major moons in our solar system. Each page has my text and NASA's images, some have sounds and movies, most provide references to addit...
 
    Gerard Kuiper, Prediction of the Kuiper Belt
  Gerard Kuiper, Prediction of the Kuiper Belt
Kuiper is considered to be the father of modern planetary science for his wide ranging studies of the solar system. Although he contributed to astrophysics, established the atmosphere of Saturn's moon Titan, and discovered Saturn's moon Miranda and N...
 
    Clyde Tombaugh, Discovered Pluto in 1930
  Clyde Tombaugh, Discovered Pluto in 1930
Clyde William Tombaugh was an American astronomer. Although he is best known for discovering the dwarf planet Pluto in 1930, the first object to be discovered in what would later be identified as the Kuiper belt, Tombaugh also discovered many asteroi...
 
    Nasa, National Aeronautics and Space Act
  Nasa, National Aeronautics and Space Act
The National Aeronautics and Space Administration (NASA) is the United States government agency that is responsible for the civilian space program as well as for aeronautics and aerospace research. President Dwight D. Eisenhower established the Na...
 
       
 
         
          2018 © Timeline Index | Webwork.Amsterdam