Launched in September 1977, the probe was sent initially to study the outer planets, but then just kept on going. The US space agency (Nasa) reports that Voyager has now entered a realm of space beyond the influence of our Sun.
This interstellar region is calculated to be more than 18 billion km from Earth, or 123 times the distance between our planet and the Sun. Voyager-1 is on course to approach a star called AC +793888, but it will only get to within two light-years of it and it will be tens of thousands of years before it does so.
Confirmation of the probe's exit from the heliosphere - the bubble of gas and magnetic fields originating from the Sun - was confirmed on Tuesday in a release by the American Geophysical Union