The idea that extraterrestrial life could exist in our Solar System got one of its earliest boosts almost half a century ago when NASA spacecraft first photographed the more intricate details of Jupiter’s icy moon, Europa.

The Voyager 2 mission captured a puzzlingly smooth surface in July 1979. It also found what astronomers have dubbed “crop circles.” On Earth, people attribute supernatural forces or alien visitors to these mysterious patterns formed from depressions in a field of wheat. But “crop circles” is also a name astronomers have given the puzzling, faint troughs on Europa’s surface. No, scientists don’t think they were made by intelligent alien life, but they do think they could be a sign that Europa might have the right ingredients to support life. If surface ice were moving around, it would create these troughs. And that morphing ice would exist because of hydrothermal activity, which could theoretically support life.

Europa’s crop circles will be better understood (hopefully) when Europa Clipper, NASA’s largest planetary mission in its 66-year history, completes the 1.8 billion mile trek through space that it began on Monday. Its mission will attempt to answer one of NASA's most ambitious questions: Are we alone in the universe?

Some debates among superhero fans will never be resolved. Superman vs. Batman. Iron Man vs. Captain America. DC vs. Marvel. But if there’s one thing everyone seems to agree on, it’s that 1986 is the most important year in comic book history. The argument why is simple — that one year saw the release of several groundbreaking comics:

1. Frank Miller’s The Dark Knight Returns, an epic story about an elderly Batman who comes out of retirement to save Gotham City in the face of American decline.
2. Alan Moore and Dave Gibbon’s Watchmen, a meticulous deconstruction of the entire superhero genre that’s also just a damn-good comic.
3. Art Spiegelman’s Maus, which retold the story of the Holocaust to terrific effect in comic book form.

All three of these comics pushed the limits of the art form with mature, gritty stories that would shape the industry for decades to come. But perhaps most crucially, they also changed the very definition of the term “comic book.”

“It became apparent that comics were a medium rather than a genre,” Gibbons, who illustrated Watchmen, tells Inverse. “They didn't have to be straightforward superhero stories or straightforward adventure stories. You could tell all kinds of stories.”

But before Gibbons and Moore could deconstruct the entire superhero genre with Watchmen and change comics forever, they had to take on the most iconic superhero of them all.