According to Dr. Grundy, Pluto is a planet. "I use the word 'planet' to refer to it, and most of the planetary science community does too," Grundy said. "Pluto's got everything I like in a planet ...

To be fair, Pluto had it coming. The word "planet" never had an official definition, and astronomers had always played fast ...

Clyde Tombaugh discovered Pluto in 1930 at Lowell Observatory in Flagstaff. Here's how Pluto won - and lost - its planetary ...

(Correction: An earlier version of this story misstated how far Pluto is from the sun. The correct number is 3.7 billion miles.) What was discovered in Flagstaff, Arizona, and killed off in Prague?

Pluto the planet came first ... argues more than 700 other objects could be considered planets depending on how the word is defined. Ultimately the International Astronomical Union, the ...

Pluto, discovered in 1930, was once considered the ninth planet in our solar system. In 2006, the International Astronomical Union reclassified Pluto as a dwarf planet because it doesn't meet all ...