An amateur astronomer discovered Pluto 95 years ago today. The former planet will complete an orbit in another 153 years. On February 18, 1930, just two weeks after his 24th birthday, Clyde ...

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." ...

“New Horizons shattered a major paradigm of planetary science,” says Alan Stern, the mission’s principal investigator. “Pluto turns out to have as much complexity as Mars or Earth, so much so that I ...

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 ...

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 ...

On Feb. 18, 1930, the young astronomer Clyde Tombaugh discovered Pluto, considered for decades a planet and “demoted ... Numerous folks were happy to snatch up a copy of Nimoy’s book ...

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 ...

Eris is more massive than Pluto but has a smaller volume ... nobody has been happy about the definition of the planet since this world was discovered. So, happy discovery day Eris, and All ...