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Celestial Object

Pluto

Dwarf Planets
Disc with a Heart-Shaped Region

A dwarf planet in the Kuiper Belt, discovered by Clyde Tombaugh. Pluto was classified as the solar system's ninth planet from 1930 until 2006, when the International Astronomical Union adopted a new formal definition of "planet" that Pluto does not meet, reclassifying it as a dwarf planet; the decision remains debated among some astronomers and the public.

Facts
Diameter (km)
2377 1
Mass
1.30 x 10^22 kg 1
Orbital Distance
39.5 AU average (about 5.91 billion km) from the Sun, on an eccentric orbit 1
Discovery Year
1930 2
Disputed
Object Type
Dwarf planet (IAU classification, 2006); planet (1930-2006 classification) 1
Classified as the ninth planet 1930-2006; reclassified as a dwarf planet by the IAU's 2006 definition, a decision some astronomers and the New Horizons mission team have publicly disputed on scientific grounds.
Classification
Catalogue
Other or Uncatalogued 1
Connections

Associated With

Ceres, Celestial Objects

Why this is disputed. Both bodies were reclassified as dwarf planets under the IAU's 2006 dynamical definition of planet, a classification a minority of planetary scientists dispute in favor of a geophysical definition; see the recorded dissent on Ceres's object-type.

Source Wikipedia (space and spaceflight articles)
Charon, Celestial Objects
Source NASA Solar System Exploration
New Horizons, Spacecraft

Performed the first close flyby of Pluto, in July 2015.

Source NASA Solar System Exploration
New Horizons Mission, Missions and Programs

Pluto was the mission's primary flyby target, reached on 14 July 2015.

Source Wikipedia (space and spaceflight articles)
Additional Source New Horizons (Wikipedia)New Horizons, lead section
Nice Model, Concepts
Orbital Resonance, Concepts

Pluto is in a 3:2 orbital resonance with Neptune.

The Moon, Celestial Objects
Source NASA Solar System Exploration

Orbited By

Charon, Celestial Objects
Source NASA Solar System Exploration

Orbits

Sun, Celestial Objects
Source NASA Solar System Exploration
Sources
1. NASA Solar System Exploration
National Aeronautics and Space Administration
  • Pluto Facts, Introduction section
    Pluto was reclassified as a dwarf planet in 2006 by the International Astronomical Union.
  • Pluto Facts, Moons section, moon list sentence
    Pluto has five known moons: Charon, Nix, Hydra, Kerberos, and Styx.
  • Pluto Facts, Introduction section, discovery sentence
    Discovered in 1930, Pluto was long considered our solar system's ninth planet
  • Pluto Facts, Introduction section, New Horizons sentence
    The only spacecraft to explore Pluto up close was NASA's New Horizons. It flew by the dwarf planet and its moons in 2015.
  • Pluto Facts, Formation section, Kuiper Belt sentence
    Dwarf planet Pluto is a member of a group of objects that orbit in a disc-like zone beyond the orbit of Neptune called the Kuiper Belt.
  • Pluto Facts, Orbit and Rotation section, orbit sentence
    Pluto's 248-year-long, oval-shaped orbit can take it as far as 49.3 astronomical units (AU) from the Sun, and as close as 30 AU.
  • Entity description, pluto catalogue classification
    A dwarf planet in the Kuiper Belt, discovered by Clyde Tombaugh.
  • Associated With: New Horizons
  • Orbited By: Charon, science.nasa.gov, Pluto Moons: Charon
  • Orbits: Sun, Pluto Facts, Orbit and Rotation section
    Pluto's orbit around the Sun is unusual compared to the planets: it's both elliptical and tilted.
  • Associated With: Charon, Pluto Facts, Moons section, double planet sentence
    Pluto and Charon are often referred to as a double planet.
  • Associated With: The Moon, Pluto Facts, Structure section, size comparison sentence
    Pluto is about two-thirds the diameter of Earth's Moon
View the Source
2. Encyclopedia Britannica: Space Exploration
Encyclopedia Britannica, Inc.View the Source
Pluto (Wikipedia)
  • Pluto, lead section (dwarf planet classification)
    Pluto (minor-planet number 134340) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune.
  • In Group: Trans-Neptunian Dwarf Planets, Lead sentence
    Pluto (minor-planet number 134340) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune.
View the Source
Wikipedia (space and spaceflight articles)
Wikimedia FoundationAssociated With: Ceres, Dwarf planet (Wikipedia) - Ceres and Pluto pairing
Quote, Associated With: Ceres, Dwarf planet (Wikipedia) - Ceres and Pluto pairing
such as Ceres, were instead classified as dwarf planets
View the Source
New Horizons (Wikipedia)
Associated With: New Horizons Mission, New Horizons, lead sectionView the Source
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