The first ever space mission to Pluto has successfully launched from Florida.
Nasa's New Horizon's probe blasted off at 7pm GMT on an Atlas 5 rocket for a nine-year journey to the ninth planet in our Solar System.
The launch was delayed by two days after windy weather and power problems made take-off conditions impossible.
Pluto is the furthest planet from Earth and it more than three billion miles away. It is the only one never to have been explored by a spacecraft.
The mission will cost $700m
A jet liner would take 1,000 years to do the same journey
An 87-year-old retired teacher from Surrey gave Pluto its name
The probe will move at a speed of 10 miles per second to get to Pluto by 2015.
The craft, which cost £396m ($700m), was the fastest spacecraft ever launched and was expected to reach Earth's moon in nine hours and Jupiter in just over a year.
New Horizon won't actually land on Pluto, but will pass close by to take pictures of the icy planet and beam them back to Earth.
It's an unmanned mission, but Nasa has put an American flag inside the craft and a CD containing the names of around half a million people who signed up to their website.