Pluto was once known as the ninth planet but was reclassified after scientists set clear criteria for planets. The key factor ...

Pluto may have lost its status as a full-fledged planet in 2006, but that doesn't mean it's a joke of a world this April Fools' Day and the folks behind Pluto TV want to make that clear.

In 2006, Pluto's planetary status was re-evaluated by the International Astronomical Union (IAU), leading to its reclassification as a "dwarf planet." The change was based on new criteria for ...

Pluto may have lost its status as a planet more than 13 years ago, but don't tell that to NASA Administrator Jim Bridenstine. Speaking at the University of Colorado recently, Bridenstine made it ...

A single day on Pluto is as long as 6.9 Earth days. Tomorrow, Feb. 18 is Pluto Day. You may ask yourself why Pluto has its own day since it is no longer considered a planet of our solar system.

Members of the International Astronomical Union, meeting in Prague in August, approved a measure that limits the definition of “planet” in a way that excludes Pluto. From now on, only a ...

Pluto has never been much of a planet — small, wired orbit, not much atmosphere — and questions about its status have been raised periodically since its discovery 76 years ...

Discovery has ordered a mini-documentary special on the dwarf planet Pluto that will take a closer look at the controversy surrounding the former planet and why it was demoted to dwarf status in ...

Once believed to be the ninth planet from the sun, Pluto lost its planet status in 2006 — causing controversy both scientifically and culturally.

In a brief video clip posted on Twitter, Bridenstine offers a somewhat tongue-in-cheek take on Pluto’s status, saying that he definitely believes Pluto is a planet if for no other reason than ...

For those who need a refresher, the “planet” debate really got into full swing in 2005 when astronomers discovered another tiny world about the same size as Pluto at the fringes of the Solar ...

You grew up learning about the nine planets, then all of the sudden there’s eight." Pluto was discovered in 1930 by astronomer Clyde W. Tombaugh at the Lowell Observatory in Flagstaff, Arizona.