It was just after 9 p.m. on June 18, 2004, at an observatory' in Arizona, U.S.A. David Tholen, an astronomer from the University of Hawaii, was scanning the sky for asteroids2 when he noticed an object headed in the direction of Earth. He and his colleagues hoped to take a closer look later that week but were unfortunately prevented by rain. By the time alo astronomers finally got another look at it in 10 December of that year, they realized they had a problem