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Earth, Pluto, Charon, and Earth's Moon compared - Space Art Illustration; Kuiper objects; plutoids; trans-Neptunian objects

Earth, Pluto, Charon, and Earth's Moon compared

  • Pluto's diameter less than 20 percent that of the Earth's (smaller than the Earth's Moon) 

  • It has less than one percent the mass

  • If you weigh 180 pounds on Earth, you would weigh 11 pounds on Pluto

  • Pluto is 30 to 48 times further from the Sun than the Earth (Pluto's orbit is highly elliptical)

  • In addition to Charon, Pluto has two smaller known moons, Nix and Hydra, discovered in 2005. Given that their estimated diameters are 100 miles or less, they are not illustrated here.

Pluto's moon Charon is over half the size of Pluto itself, leading astronomers to originally classify the Pluto-Charon system as a "double planet." They were also considered "binary planets" because the smaller Charon doesn't actually orbit around Pluto, rather Pluto and Charon orbit a common gravitational center (the "barycenter') located above Pluto's surface.

In 2006 the International Astronomical Union (IAU) demoted Pluto from its status as the Solar System's 9th planet to a dwarf planet, and as the IAU has yet to formalize a definition for binary dwarf planets, Charon is currently regarded as a satellite of Pluto. Next to the recently discovered dwarf planet Eris, Pluto is the second-largest known dwarf planet in the Solar System.

As no space probe has yet visited Pluto*, nobody is sure what this dwarf planet looks like close up. The Hubble Space telescope has revealed that Pluto's surface displays areas of marked contrast second only in intensity to Saturn's satellite Iapetus

* NASA's robotic space probe New Horizons is currently en route to Pluto. Launched in 2006, the probe is scheduled to fly to within 7,000 miles of Pluto in 2015.


Copyright Walter B. Myers. All rights reserved.

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