Voyager-1 spacecraft 'leaves Solar System'
12 September 2013 Last updated at 22:06 BST
The Voyager-1 spacecraft has become the first manmade object to leave the Solar System.
Scientists say the probe's instruments indicate it has moved beyond the bubble of hot gas from our Sun and is now moving in the space between the stars.
Launched in 1977, Voyager was sent initially to study the outer planets, but then just kept on going.
Today, the veteran Nasa mission is almost 19 billion km (12 billion miles) from home.
Pallab Ghosh reports.