A distant, icy rock whose discovery shook up the solar system and led to Pluto's planetary demise has been given a name: Eris. The christening of Eris, named after the Greek goddess of chaos and strife, was announced by the International Astronomical Union on Wednesday. Weeks earlier, the professional astronomers' group stripped Pluto of its planethood under new controversial guidelines. Since its discovery last year, Eris, which had been known as 2003 UB313, ignited a debate about what constitutes a planet. Astronomers were split over how to classify the object because there was no universal definition. Some argued it should...