Astronomers are investigating a potential hidden planet, dubbed Planet Y, far beyond Neptune. Its gravitational pull is ...

In 2006, the International Astronomical Union (IAU) voted on the definition of a planet. Famously, Pluto no longer met the criteria and was demoted to a dwarf planet. Things have been a bit of a mess ...

For many people, the definition of a planet was only made clear in 2006, when the spunky world Pluto was demoted from a planet to a dwarf planet. Now, a team of astronomers is pushing for “planet” ...

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 ...

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights. Samantha Lawler, Assistant professor, Astronomy, ...

NASA has released a new video showing what it might be like to land on Pluto with a brand-new view of the dwarf planet's surface. The space agency’s New Horizons spacecraft spent about six weeks in a ...