Continuing analysis from the data gathered by the Kepler space telescope shows that of all the stars in our galaxy that our similar to our sun, possibly one out of every five has an Earth-size planet orbiting in the habitable zone—with temperatures that permit liquid water. That could mean billions of planets out there capable of supporting life that wouldn’t be completely strange to us. We don’t have to imagine unrecognizable life forms that breathe chlorine or methane or are made of silicon (although those are still possible, I suppose).

Why does this news excite us? Unless we manage to make an end run around the laws of physics—inventing warp drive, harnessing wormholes, or something equally exotic and improbable—we’ll never be able to get to more than a handful of those planets. They’re just too far away. Perhaps we could found a colony or two, but it’s really the thought of other intelligent life that’s the compelling part, isn’t it? Is there something comforting in the thought that we’re not alone in the universe—that somewhere “out there” others are looking back in our direction and asking the same questions? Even if we will never meet?

It’s fun to remember all of the different ways we’ve imagined alien species. For most of TV and movie history, there were the limitations of makeup, costumes, and puppetry. Think of the green Orion slave girls of Star Trek, or Mr. Spock himself, or Klingons and Romulans, Cardassians and Ferengi. Give them some prosthetics and suddenly they’re children of another star. Aliens from lower-budget shows like Lost In Space were embarrassingly cheesy. Dr. Who brought us dozens of roughly humanoid species, or human-sized robotic entities like Daleks and Cybermen. And then there’s one of the most popular tropes of all: aliens that make themselves look exactly like humans so they can a) hide among us, or b) communicate without frightening us. I hope the guy who thought of that one got a juicy bonus from his producer.

With computer graphics, Hollywood can make aliens look like anything they want, but so much depends on whether they’re meant to be our allies or enemies. Wookies and Ewoks are just teddy bears on different scales. E.T. the Extraterrestrial is ugly but cuddly. And then there are the willowy, large-eyed hairless aliens of The X-Files, Close Encounters of the Third Kind and others: they’re like us but smarter-looking because they don’t have to shave anymore and obviously have machines to do all the work, eliminating the need for actual muscles. But if an alien species is supposed to be an implacable enemy, they look like something from the insect world: the Bugs of Starship Troopers and the Buggers of Ender’s Game, or even the acid-dripping Aliens that made Sigourney Weaver’s life Hell. Somehow there’s never a giant can of Raid around when you need one.

The truth is, even our wildest imaginations couldn’t have come up with all of the bizarre manifestations of life to be found right here on our home planet, from the hidden depths of rain forests to deep-ocean volcanic rifts (though hopefully tube-worms aren’t intelligent). So we don’t have much hope of correctly imagining what’s “out there”. Is it still comforting to think of life on other planets? Give me your answer the next time you wake up from a nightmare about a slimy demon bursting from your chest.