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 ...

Humans should look to planetary alignments outside of the solar system when searching for signatures of extraterrestrial communications, scientists say. The nascent search for radio transmissions from ...