The spacecraft Voyager 2 left the heliosphere and travelled into interstellar space over the course of a day in November 2018, according to a suite of papers published today by scientists working on the mission.
The spacecraft was launched in 1977 along with its twin Voyager 1, which crossed-over into interstellar space seven years ago. Scientists analysing data from Voyager 2 have found both similarities and differences to the crossing of Voyager 1.
The Sun is surrounded by a huge bubble called the heliosphere that is inflated by the supersonic solar wind of charged particles emitted by the Sun. The edge of this bubble is called the heliopause, which is where the outgoing solar wind is halted by the interstellar wind of charged particles.
Both Voyager missions crossed the heliopause on the windward side of the bubble but at different locations. Voyager 1 left the northern hemisphere of the heliosphere and Voyager left the southern hemisphere at locations separated by about 160 au (1 au is the distance from Earth to the Sun).
Voyager 1’s departure point was about 122 au from the Sun, while Voyager 2 exited at 119 au from the Sun. According to ...