Voyager 2's 1986 flyby of Uranus, the main source of our knowledge of the icy planet, could have come at the same time as a weird plasma burst from the sun.

For decades, the observation has been an enigma. But not anymore. Recent analysis of Voyager's old data found that extreme solar wind — a flow of particles shooting out from the sun — impacted the environs around Uranus and created the abnormal episode.