Launched 36 years ago, Voyager 1 and its twin Voyager 2 made an unprecedented tour of the outer planets, returning spectacular data from their journey. The first Voyager sped out of the solar system in 1980 and it has since been edging closer and closer to interstellar space. The probe is currently out more than 120 times the distance between the Earth and the sun.

Scientists initially thought that Voyager’s transition into this new realm, where effects from the rest of the galaxy become more pronounced, would be gradual and unexciting. But it’s proven to be far more complicated than anything researchers had imagined, with the spacecraft now encountering a strange region that scientists are struggling to make sense of.