Immediately after its 2008 launch, NASA’s Interstellar Boundary Explorer, or IBEX, spotted a curiosity in a thin slice of space: More particles streamed in through a long, skinny swath in the sky than anywhere else. The origin of the so-called IBEX ribbon was unknown — but its very existence opened doors to observing what lies outside our solar system.
Humanity has visited Uranus only once, and that was exactly 30 years ago. NASA’s Voyager 2 spacecraft got its closest look at the mysterious, distant, gaseous planet on 24 January 1986. The probe sent back stunning images of the coldest planet known in our solar system and its moons during the flyby, which allowed for about 5½ hours of close study.