New Horizons lifted off atop a Lockheed Martin Atlas V rocket at 2:00 p.m. ET from the Cape Canaveral Air Force Station in Florida to begin a 10-year, 3-billion-mile mission.
It took Apollo 11 three days to reach the moon in 1969. New Horizons will fly by it about nine hours and reach Jupiter in a little more than a year, the space agency said.
Planetary astronomers now believe Pluto is a Kuiper Belt object.