Radioactivity and gravity may be why the strange football-shaped dwarf planet known as Haumea and its moons are unexpectedly sheathed in crystalline ice, shining in space, researchers suggest. Haumea, named after the Hawaiian goddess of childbirth, orbits the sun beyond the path of Neptune, with two moons in orbit around it named Hi'iaka and Namaka, two of the deity's daughters. Haumea is a bizarre dwarf planet world shaped like a cigar, or perhaps an American football, measuring about 1,200 miles (2,000 kilometers) long, and makes one full rotation in less than four hours. This is one of the fastest rotation...