There might be many more planets that could be home to aliens than we thought, according to a new study.
For years, scientists have searched for life in the “habitable” or “goldilocks” zone – where it is neither too hot or too cold to have liquid water. Those worlds have been the centre of our search for alien life, since we believe that liquid water is necessary to make a planet habitable.
Many of the planets in other solar systems that we have found do not fit into that criteria. That has meant that researchers have thought that a large number of the worlds we have found are probably inhospitable for alien life.
Now, however, new research has suggested that criteria could be too strict. There might be other worlds that allow for liquid water that we have overlooked it suggests.
On planets that are tidally locked – where one side of the world stays oriented towards its star, with the other always in night – the heat might circulate around the planet enough to allow for liquid water, the new study suggests. It used a model to understand how the climate on such a planet would work.
Heat would come around from the day side of the planet and keep the night side above freezing, the research suggests. As such, the number of possibly habitable environments might be larger than we realise.
That could mean that some of the planets recently spotted by Nasa’s James Webb Space Telescope, which appear to have water vapour and other volatile gases, could actually be in the safe range to have water on their surface.
The work also suggests that planets that were thought to be on the other extreme end – too far away to have liquid water – could also actually be habitable. On those planets, liquid water could be stored between layers of thick ice, meaning that there might be even more worlds that could be home to alien life.
The work is reported in a new paper, ‘Exoplanets beyond the Conservative Habitable Zone. I. Habitability’, published in the journal The Astrophysical Journal.
