The NASA spacecraft Voyager 1 has become the first man-made object to leave the solar system and enter the cold, obscure space between the stars.
Scientists say new data proves it entered interstellar space over a year ago.
In the late 1970s the Voyager mission was initially to study other planets such as Jupiter and Saturn.
It kept on going – the man who has led the mission from the start is delighted.
“Well first of all we got there. I mean, this is something we all hoped when we started on this 40 years ago, that this would happen,” said Voyager project scientist Ed Stone. “None of us knew anything could last as long as the two Voyager spacecraft.”
Another NASA scientist, Gary Stark, explained where Voyager had got to.
“We’ve exited the material created by the sun and we’re truly in an alien environment. The material in which Voyager finds itself is not created by the sun. It’s created in fact by our neighbouring stars supernova remains and so forth,” he said.
At its launch in September 1977, Voyager 1 carried messages from world dignitaries such as then US President Jimmy Carter, as well as recorded sounds and music to communicate with any life form it might come across.
36 years and nearly 19 billion kilometres later, Voyager is still sending faint signals back to base.
The plutonium batteries are due to die by 2020 but it’s thought Voyager 1 may continue rattling through space for billions of years.