Pluto Becomes a 'Dwarf Planet' Under Astronomers' New Definitions

By SAM KEAN

"My very excellent mother just served us nine." It doesn't quite work without "pizzas" at the end. Nor do other schoolchild mnemonics for remembering the planets of the solar system, now that Pluto has been demoted from that rank.

Members of the International Astronomical Union, meeting in Prague, approved...