The last and only time astronomers got a close look at Neptune’s moon Triton was in 1989, when Voyager 2 sped by, taking images of just one side of the moon. But that brief encounter revealed plumes of material shooting out from a world so distant and cold that any activity was immediately fascinating. Scientists now think the moon has an underground ocean. This makes it a prime target for finding potential alien life in a frozen zone of the solar system well outside the standard Goldilocks