Nasa’s Voyager 2 has become only the second human-made object to reach the space between stars.
Nasa said that the spacecraft left the region of the sun’s influence last month and is now beyond the outer boundary of the heliosphere, about 11 billion miles from Earth. It is trailing Voyager 1, which reached interstellar space – the vast, mostly empty area between star systems – in 2012.
Nasa said the evidence that Voyager 2 had left the heliosphere was provided by an onboard instrument called the Plasma Science Experiment, which measures solar wind. On 5 November, the device recorded a steep decline in the speed of solar wind particles, and had not observed any at all since that date. Other instruments on Voyager 2 have corroborated the theory.
According to Nasa, the Voyagers are still technically in our solar system. Scientists maintain the solar system stretches to the outer edge of the so-called Oort Cloud, a sphere of icy bodies millions of miles away which will take thousands of years to traverse.
“Working on Voyager makes me feel like an explorer, because everything we’re seeing is new,” said John Richardson, a principal research scientist at the Massachusetts Institute of Technology. “We’re still seeing things that no one has seen before.”
“Voyager has a very special place for us,” said Nicola Fox, director of the heliophysics division at Nasa. “Our studies start at the sun and extend out to everything the solar wind touches. To have the Voyagers sending back information about the edge of the sun’s influence gives us an unprecedented glimpse of truly uncharted territory.”
The Voyagers launched from Cape Canaveral, Florida, in 1977. Despite the great distance, flight controllers are still in contact with Voyager 2.
