Add Yahoo as a preferred source to see more of our stories on Google. Guests visting the Lowell Observatory in Flagstaff, Arizona during the I Heart Pluto Festival gaze at celestial objects from the ...

Pluto was reclassified as a dwarf planet in 2006. This video explains the scientific reasoning behind its demotion, the IAU’s strict criteria for planet status, and why Pluto remains fascinating ...

Arizona – and Flagstaff specifically – has long considered itself the home of Pluto. After all, Percival Lowell, the namesake of the state's most prominent observatory, was not only one of the first ...

NASA Administrator Jared Isaacman has reiterated his support for Pluto to be reclassified as a planet. Pluto was downgraded to a dwarf planet in 2006 because it has not cleared its orbital path of ...

Pluto is no longer a planet, but why did it lose that title? The change came in 2006 from the International Astronomical Union, which wanted a clear definition of what a planet actually is. Before ...

Back in 2006, the International Astronomical Union determined that the definition of a planet is one where a body must “clear” its orbit. This means to be classed as a planet the object must be the ...

For no explainable practical reason, humans are enamored with – and even empathetic toward – specific inanimate objects. Our first car. A choice coffee mug. And for a particular subset of the ...