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17 of the coolest space discoveries

Photos Logo Photos | Slide 1 of 17: IN SPACE - JULY 14: In this handout provided by the National Aeronautics and Space Administration (NASA), Pluto nearly fills the frame in this image from the Long Range Reconnaissance Imager (LORRI) aboard NASA's New Horizons spacecraft, taken on July 13, 2015, when the spacecraft was 476,000 miles (768,000 kilometers) from the surface. This is the last and most detailed image sent to Earth before the spacecraft's closest approach to Pluto. New Horizons spacecraft is nearing its July 14 fly-by when it will close to a distance of about 7,800 miles (12,500 kilometers). The 1,050-pound piano sized probe, which was launched January 19, 2006 aboard an Atlas V rocket from Cape Canaveral, Florida, is traveling 30,800 mph as it approaches. (Photo by NASA/APL/SwRI via Getty Images)

Pluto is discovered

On Feb. 18, 1930, astronomer Clyde W. Tombaugh discovered Pluto at the Lowell Observatory in Flagstaff, Arizona, U.S. Named after the Roman god of the underworld, Pluto is about 1,400 miles (2,380 kilometers) wide and takes 248 years to complete one revolution of the sun. It's temperature of -378 to -396 degrees Fahrenheit (-228 to -238 degrees Celsius) makes Pluto inhospitable. Considered the ninth planet of the solar system at the time of its discovery, Pluto was reclassified as a dwarf planet in 2006 by the International Astronomical Union because its orbit overlapped with that of Neptune’s.

© NASA/APL/SwRI/Getty Images
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