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” ...

Until 2015, Pluto, the former ninth planet of the classical solar system, was largely a mystery—a tiny speck 3.6 billion miles from the sun. When NASA's New Horizons spacecraft arrived at the ...

Pluto hasn't been a planet for almost 20 years. In the early 2000s, scientists discovered several objects of a similar size to Pluto. So, during the summer of 2006, members of the International ...

Arizona has declared Pluto its “official state planet” — despite it being relegated to “dwarf planet” status nearly two decades ago. Gov. Katie Hobbs signed legislation on Friday and afterward dodged ...

A new formation theory for Pluto's moon Charon could explain why Pluto is geologically active. Illustration incorporates NASA New Horizons terrain imagery. Pluto — demoted to dwarf planets status in ...

The science community may be ecstatic over the discovery of a ninth planet, but the former planet "Pluto" had a totally different reaction. Hours after scientists announced there's solid evidence of ...

Forbes contributors publish independent expert analyses and insights. An award-winning reporter writing about stargazing and the night sky. Astronomers have found a distant celestial body — ...

Add Yahoo as a preferred source to see more of our stories on Google. A huge heart-shaped feature on the surface of Pluto has intrigued astronomers since NASA’s New Horizons spacecraft captured it in ...