Eight years ago today, on 5 November 2018, NASA's Voyager 2 crossed the heliopause, becoming only the second human-made object to enter interstellar space, after Voyager 1 on 25 August 2012. At roughly 119 AU (about 11 billion miles) from the Sun, its still-working Plasma Science Experiment delivered the first direct plasma measurements of that boundary.

Launched on 20 August 1977, sixteen days before Voyager 1, Voyager 2 remains the only spacecraft to have visited Uranus (1986) and Neptune (1989). It is still returning data from about 144 AU, after the plasma instrument was powered down in September 2024 to stretch the mission's remaining power.