Aliens could be hiding in 'terminator zones' on planets outside the Solar System.
Aliens could be hidden on distant planets in 'terminator zones'
Many exoplanets are tidally locked, which means that one side always faces the star they orbit and the other is in constant darkness.
Astronomers have discovered that these planets have a band around them that could harbour water - a vital ingredient for life.
The dividing line between the exoplanet's day and night sides is called the 'terminator zone' and boffins believes it is a 'sweet spot' as the temperature could sustain alien life.
Dr. Ana Lobo, of the University of California, said: "The dayside can be scorching hot, well beyond habitability, and the night side is going to be freezing, potentially covered in ice.
"You could have large glaciers on the night side. You want a planet that's in the sweet spot of just the right temperature for having liquid water.
"We are trying to draw attention to more water-limited planets which despite not having widespread oceans could have lakes or other smaller bodies of liquid water and these climates could actually be very promising.
"By exploring these exotic climate states we increase our chances of finding and properly identifying a habitable planet in the future."