It's showtime for Pluto. NASA's New Horizons spacecraft has traveled 3 billion miles and is nearing the end of its nine-year journey to Pluto. Sunday, it begins photographing the mysterious, ...

The spacecraft team that brought us close-ups of Pluto will ring in the new year by exploring an even more distant and mysterious world. NASA's New Horizons spacecraft will zip past the scrawny, icy ...

FLAGSTAFF – Clyde Tombaugh sat in the Orpheum Theater that fateful night in February 1930, waiting for clouds to pass before the 24-year-old astronomer could return to Lowell Observatory to confirm ...

Pluto sits far out in the Solar System, small and dim, moving at a pace that barely fits human timelines. It was found in 1930, at a time when astronomy still relied on patient observation and ...