Aliens have always been bound to sci-fi, because a lot of things need to go right in order for extraterrestrial beings visiting us to be possible. The two main criteria we can think of are they would have to be close enough to travel to Earth, and they would need to live on a planet that's conducive to supporting life. It turns out that may be more possible than we previously thought, as NASA just discovered that orbiting a star 40 light-years away are seven planets that just might be livable (via Vox).
Trappist-1 is a dwarf star that's about a tenth the mass of our Sun and a thousandth as bright. That makes it pretty cool (in temperature, not swag), meaning that planets can orbit it pretty closely while remaining in a habitable zone. By "habitable," we mean that there's great potential for liquid water to exist on their surfaces.
Three of the planets—e, f, and g, as labeled above—are in the most habitable zone, meaning water could most likely exist on them. Water may be possible on the other four planets as well, depending on the composition of their atmospheres, NASA astronomers said. This solar system seems very different from our own, mostly in its size: The distance between Trappist-1 and its most distant orbiting planet isn't much greater than that between Jupiter and Callisto, its most distant moon.
Naturally, as we established from the very beginning, habitable planets have us very excited about the possibility of aliens, and even those in the scientific community share our fan-like enthusiasm. Weekly science journal Nature has already published a sci-fi story that stars a space adventurer on one of Trappist-1's planets.
In the paper announcing the discovery, the scientists said we can expect to know a lot more about these planets "in a few years," but until then, let's leave our imaginations unbridled as we envision alien societies on these neighboring planets, and the peace, conflict, and adventure that exists among them.
You can watch the whole press conference right here!