A "minor planet" with the prosaic name 2006 SQ372 is just over two billion miles from Earth, a bit closer than the planet Neptune. But this lump of ice and rock is beginning the return leg of a 22,500-year journey that will take it to a distance of 150 billion miles, nearly 1,600 times the distance from the Earth to the Sun, according to a team of researchers from the Sloan Digital Sky Survey (SDSS-II). The discovery of this remarkable object was reported today in Chicago, at an international symposium titled "The Sloan Digital Sky Survey: Asteroids to Cosmology." A...