He called this hypothetical world "Planet X." "In some ways, Pluto's more of a planet than some of the other established planets, like Mercury." ...

They did, and the discovery of Planet X was announced on March 13, 1930. An 11-year-old English schoolgirl, Venetia Burney, suggested the name Pluto, the god of the underworld. Tombaugh’s ...

If you answered "Pluto's planethood," your grasp of the astronomical is excellent. Feb. 18 marks the 95th anniversary of the discovery of our outermost planet-not-planet. Here's what to know about ...

A blue atmosphere, smooth areas, and youthful mountain ranges - this dwarf planet is full of surprises. When NASA's New Horizons probe flew past Pluto in July 2015, the images it returned astonished ...

Pluto was discovered at Lowell Observatory in Flagstaff, Arizona in 1930 and was considered our ninth planet until 2006. The International Astronomical Union reclassified Pluto as a dwarf planet ...

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 ...

Viewed in this longer context, the previously modern idea of having nine planets, which came about in the 1960s and lasted only until 2006, was a blip on the screen. And if you are still a Pluto ...