A team of astronomers claims to have sniffed out a “biosignature” in the atmosphere of a distant planet called K2-18b. But not everyone agrees that it signals life. An illustration shows what ...

You’ve traveled thousands of light-years through interstellar star systems. And now you’re stranded on a planet you know nothing about. As long as you’ve got oxygen, water and food aboard your ...

The Search for Extraterrestrial Intelligence (SETI) focuses on finding technosignatures—potential signs of alien technology. If we look carefully, we might have a chance at detecting their ...