On Aug. 24, 2006, the International Astronomical Union voted to strictly define a planet, which ultimately downgraded Pluto from the ninth planet from the sun to a dwarf planet — causing controversy ...

Pluto may have been demoted to non-planet status, but it still commands a court of five moons, as is fitting for the king of ...

Pluto, once thought to be a frozen and lifeless world drifting on the edge of our solar system, may be harboring one of its ...

When NASA’s New Horizons mission flew past Pluto in 2015, it gave humanity our first glimpse of a colossal depression on the isolated world. It's named Sputnik Planitia. Comparable in size to the ...