Though Pluto has formally been considered a dwarf planet for almost two decades, it still has many lessons left for planetary scientists — including hints about how the solar system formed.

Arizona Gov. Katie Hobbs signed a bill making Pluto the official state planet. It was discovered at an observatory in Arizona, but was downgraded to a dwarf planet in 2006.

Pluto was discovered in 1930 in Arizona, but in 2006 scientists decided to cut Pluto from the planetary line up. Here is why Pluto isn't a planet.

Pluto was downgraded to dwarf planet over 10 years ago, but it's something that still seems so damn unfair. How do you take away its planet status after 76 years? On the other hand, science is ...

In the time Pluto was found, classified as a planet and reclassified as a dwarf planet, it has not completed one orbit. One year on the distant ice planet is 248 Earth years, and one day is 153 ...

But why isn't Pluto considered a planet anymore? It starts with the definition of a planet — or lack thereof. Before 2006, there weren't strict criteria for a planet.

The astronomers at Lowell Observatory in Arizona are showing Pluto some love on the 95th anniversary of its discovery, regardless of whether we call it a planet or not.

In 2006, astronomers ‘demoted’ Pluto from a major planet in the solar system to a dwarf planet. But was Pluto snubbed? Our experts answer.

More than 15 years after Pluto was demoted to dwarf planet, the debate, even among scientists, continues. By Kenneth Chang Who doesn’t love Pluto? It shares a name with the Roman god of the ...

Pluto was the little planet that could — until it couldn’t. Discovered in 1930 at Lowell Observatory in Flagstaff, Arizona , Pluto was hailed as the ninth planet in our solar system.

When the International Astronomical Union (IAU) demoted Pluto from a planet to a dwarf planet in 2006, it surprised a lot of people, including some scientists.