For decades, Pluto was our solar system's ninth planet. This video explains the scientific journey that led to its ...

Once the quirky underdog of our solar system, Pluto held planetary status until 2006, when it got a cosmic demotion that still stings space fans. Discovered in 1930, Pluto was the ninth planet for ...

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Many Americans grew up with this as the definitive planetary lineup and created clever mnemonic devices to memorize them in ...

PRAGUE, Czech Republic — Leading astronomers declared today that Pluto is no longer a planet under historic new guidelines that downsize the solar system from nine planets to eight. After a tumultuous ...

NASA's New Horizons spacecraft captured this high-resolution enhanced color view of Pluto that is inserted beneath the Short Wave logo. The image combines blue, red and infrared images taken by the ...

The year was 2015. After traveling billions and billions of miles through the Erebus, New Horizons encounters the boatman, and the somber lord of the departed. The spacecraft could have been called ...

On Aug. 24, 2006, the International Astronomical Union voted to strictly define a planet, which ultimately downgraded Pluto from the ninth planet from the sun to a dwarf planet — causing controversy ...