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 ...

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

A kindergartener in 2005 and a kindergartener in 2006 would have learned very different facts about the number of planets in the solar system. 2006, of course, was the year Pluto was reclassified as a ...

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 ...