Aliens on distant exoplanets? Scientists say 'terminator zones' could harbour life

A recent study was conducted by astronomers from the University of California, Irvine in which they suggested the possibility of aliens hiding in special 'terminator zones' on distant exoplanets, where the temperature is not too hot or cold.

Various exoplanets, which are outside our solar system, remain tidally locked and hence, one side always continues to face the star around which they orbit and the other side remains permanently in darkness.

The astronomers, in their study, found that there is a band around these planets in which there is a possibility that they are harbouring liquid water which is the main ingredient for life.

This band is called the 'terminator zone' where the terminator acts as the dividing line between the day side and night side of the exoplanet.

The scientists said that the water is likely to remain frozen on the cold night side and is likely to evaporate due to heat on the light dayside.

“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 at the night side. You want a planet that's in the sweet spot of just the right temperature for having liquid water,” said lead author, Dr Ana Lobo said.

“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,” she added.

Lobo added that one of the major findings was understanding what kind of terminator zone can retain liquid water on the planet. The team discovered that if water is mostly covering the planet then the water facing the star is most likely to evaporate and the entire planet will be covered in a thick layer of vapour. However, this effect shouldn't take place if there's land.

“Ana has shown if there’s a lot of land on the planet, the scenario we call ‘terminator habitability’ can exist a lot more easily,” said Aomawa Shields, UCI associate professor of physics & astronomy.

“These new and exotic habitability states our team is uncovering are no longer the stuff of science fiction — Ana has done the work to show that such states can be climatically stable,” Shields added.

Identifying terminator zones as a potential place for harbouring life also means that astronomers are required to adjust the way exoplanet climates are being studied for finding signs of life because there is a chance of biosignatures life creates being present in few parts of the atmosphere of the planet.