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Tour the solar system: Pluto and the Kuiper Belt

Get the details on this oddball planet discovered in 1930 and the various other worlds beyond Neptune that later influenced its planetary status.
Pluto_HST
Pluto's mottled surface as seen by the Hubble Space Telescope.
NASA/ESA/Marc Buie (SwRI)
Pluto doesn’t look like much from Earth. It glows at 14th magnitude, making it a thousand times dimmer than the faintest objects visible with naked eyes. Even the sharp eye of the Hubble Space Telescope reveals little more than mottled patches of white, orange, and black.

It doesn’t appear bright or show much detail for two reasons. First, it’s tiny, with a diameter of just 1,485 miles (2,390 kilometers) and a mass 500 times smaller than Earth’s. Second, Pluto lies far away. Its 248-year orbit keeps it at an average distance of 3.67 billion miles (5.91 billion kilometers) from the Sun. From this great distance, the Sun appears as no more than a point of light, although it would be a brilliant one, shining hundreds of times brighter than a Full Moon does from Earth.

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