Beyond the rocky inner planets and the gas giants lie the ice worlds. At over a billion miles from the sun, Uranus and Neptune intrigue scientist from afar. Some 30 years ago NASA’s Voyager 1 & 2 journeyed to this bizarre realm, revealing that Uranus is tipped on its side, and Neptune is enveloped by supersonic winds. Pushing further, New Horizons conducted the first flyby of Pluto in 2015. Its dazzling images revealed Pluto’s jagged ice mountains and an underground ocean that changed everything scientists thought about the beloved dwarf planet. Now, NOVA takes you inside the missions that rewrote the story of the outer solar system.

Watch NOVA: The Planets: Ice Worlds, tonight at 9pm on WGBH 2.