And one day, he did.

Fast forward to a summer afternoon in July 2007. Ye, now 19 years old and a student of meteorology at China's Sun Yat-sen University, bent over his desk to stare at a black-and-white star field. The photo was taken nights before by Taiwanese astronomer Chi Sheng Lin on "sky patrol" at the Lulin Observatory. Ye's finger moved from point to point--and stopped. One of the stars was not a star, it was a comet, and this time Ye saw it first.

Comet Lulin, named after the observatory in Taiwan where the discovery-photo was taken, is now approaching Earth. "It is a green beauty that could become visible to the naked eye any day now," says Ye.