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 ...

A researcher has used advanced models that indicate that the formation of Pluto and Charon may parallel that of the Earth-Moon system. Both systems include a moon that is a large fraction of the size ...

"Please make Pluto a planet again. I really want it to be a planet again," Kayla begins, eliciting a response from the NASA ...

A 10-year-old's earnest letter to NASA, politely requesting Pluto's planet status be reinstated, captured global attention.