Pluto Fact File

Pluto and Cheron

Pluto was discovered by American astronomer Clyde Tombaugh in 1930. Pluto takes 248 years to orbit the Sun. Due to it's highly elliptical orbit, Pluto can get as close to the sun as 4,436,820,000 km and then move away to a distance of over 7 billion kilometers.

Pluto is about two-thirds the diameter of Earth's Moon and may have a rocky core surrounded by a mantle of water ice. Due to its lower density, its mass is about one-sixth that of the Moon. Pluto appears to have a bright layer of frozen methane, nitrogen, and carbon monoxide on its surface. While it is close to the Sun, these ices thaw, rise, and temporarily form a thin atmosphere, with a pressure one one-millionth that of Earth's atmosphere. Pluto's low gravity (about 6 percent of Earth's) causes the atmosphere to be much more extended in altitude than our planet's. Because Pluto's orbit is so elliptical, Pluto grows much colder during the part of each orbit when it is travelling away from the Sun. During this time, the bulk of the planet's atmosphere freezes.

Pluto has a satellite (moon), named Charon. Charon is almost half the size of Pluto and shares the same orbit. Pluto and Charon are thus essentially a double planet. Charon's surface is covered with dirty water ice and doesn't reflect as much light as Pluto's surface.

In 2006, during a meeting of the IAU (International Astronomical Union) the definition of a planet was redefined. As a result Pluto lost it's status as a planet and was reclassified as a dwarf planet.

Pluto: Facts & Figures

  • Average Distance from the Sun: 5,906,380,000 km
  • Perihelion (closest): 4,436,820,000 km
  • Aphelion (farthest): 7,375,930,000 km
  • Equatorial Radius: 1,151 km
  • Equatorial Circumference: 7,232 km
  • Mass: 13,000,000,000,000,000,000,000 kg
  • Volume: 6,390,000,000 km3
  • Density: 2 g/cm3
  • Surface Area: 16,650,000 km2
  • Equatorial Surface Gravity: 0.81 m/s2
  • Escape Velocity: 4,570 km/h
  • Length of Day: 153.3 hours
  • Length of Year: 90,553 Earth days (247.92 Earth years)
  • Mean Orbit Velocity: 17,096 km/h
  • Orbital Eccentricity: 0.2488
  • Orbital Inclination to Ecliptic: 17.14 degrees
  • Equatorial Inclination to Orbit: 119.61 degrees
  • Orbital Circumference: 32,820,000,000 km
  • Minimum/Maximum Surface Temperature: -233/-223 °C
  • Number of Moons: 1

Source: NASA