Voyagers leaving solar system, illustration. The Solar System is at centre, surrounded by the heliosphere (dark and light blue), a protective bubble created by the Sun that extends well past the orbit of Pluto. At right are NASA's Voyager 1 and Voyager 2 probes, which have now left this protective bubble and are in the interstellar plasma (a stream of charged ions and particles), rather than the solar plasma. These plasmas flow in different directions, with a wave bow shock structure formed as the Sun moves through space. Voyager 1 crossed the heliopause, the outer edge of the heliosphere boundary, in August 2012. Voyager 2 crossed the heliopause in November 2018. The probes were launched from Earth in 1977, and are now the most distant man-made objects.