Neptune, Pluto. Pluto was last and least of them. An icy dwarf only half the size of the United States, it was on average 3.7 billion miles from the sun. It also has a decidedly strange orbit that ...
"That was based on some irregular motions, or apparent irregular motions, of [Uranus and Neptune]." He called this hypothetical world "Planet X." "In some ways, Pluto's more of a planet than some ...
For decades, it captivated imaginations with its icy surface and distant orbit beyond Neptune. But in 2006, Pluto’s planetary reign came to an end when the International Astronomical Union ...