Earth is the only planet we know that has life, so it's easy to think that any other habitable planet must look like it.
Indeed, the study of exoplanets (planets outside of our solar system) often concentrates on looking for Earth's "twins".
But the universe is a weird and varied place: could some different world be habitable too?
According to a study from the Catholic University of Leuven, Belgium, the answer is yes!
If there's any chance that a planet has liquid water on its surface, it's deemed habitable.
"You need liquid water for life," says Doctor Ludmila Carone, one of the authors. "But also, at the current stage, we have not found a planet with surface water yet. It's a broad, crude criterion for...