The Voyager 1 spacecraft is getting one step closer to reaching interstellar space as the probe is about to enter the Heliopause. Since its launch on September 5, 1977, the probe has reached a distance of about 17.3 billion kilometers from the Sun. Voyager 1 has now crossed into an area where the solar wind has turned the corner, and is expected to reach interstellar space within about four years.
The venerable Voyager spacecraft are truly going where no one has gone before. Voyager 1 has now reached a distant point at the edge of our solar system where it is no longer detecting the solar wind. At a distance of about 17.3 billion km (10.8 billion miles) from the Sun, Voyager 1 has crossed into an area where the velocity of the hot ionized gas, or plasma, emanating directly outward from the sun has slowed to zero. Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars.
The event is a major milestone in Voyager 1′s passage through the heliosheath, the turbulent outer shell of the sun’s sphere of influence, and the spacecraft’s upcoming departure from our solar system.