Scientists have found around 4,000 planets that are similar to Earth and orbit Sun-like stars. However, only some of them could be capable of fostering life. But how can they be identified? Scientists might have an answer.
Discovering water is most important
A team of researchers from the University of British Colombia (UBC) is trying to understand how geology could help them identify which planets can foster life, changing the way astronomers look for water in the universe. The search for liquid water will be the most important.
“The discovery of any planet is pretty exciting, but almost everyone wants to know if there are smaller Earth-like planets with iron cores,” said Dr. Brendan Dyck, lead author of the study. “We typically hope to find these planets in the so-called ‘goldilocks’ or habitable zone, where they are the right distance from their stars to support liquid water on their surfaces.”
Discovering planets in the ‘habitable zone’ can be a way to isolate Earth-like planets, but that isn’t enough to determine whether life can sustain on these surfaces. But this parameter will help them rule out less likely planets.
Can Mars sustain life?
Dyke compares it to Mars, which is within the habitable zone but doesn’t have water on its surface. Theoretically, Mars could have liquid water, but for some reason, it lacks water despite being at a suitable position in the solar system.
“Our findings show that if we know the amount of iron present in a planet’s mantle, we can predict how thick its crust will be and, in turn, whether liquid water and an atmosphere may be present. It’s a more precise way of identifying potential new Earth-like worlds than relying on their position in the habitable zone alone,” Dr. Dyke added.
Besides, scientists have detected atmospheres on large exoplanets, and with James Webb Telescope they will be able to study the atmosphere of Earth-like exoplanets. But new studies show that the presence of oxygen isn’t enough to confirm life on an exoplanet.
The study suggests that relying on Earth’s model for a planet’s atmospheric evolution could be misleading. In its early days, Earth didn’t have oxygen in abundance, and it was only created as a waste product by early life forms. Only after the photosynthesis evolution, oxygen became so useful.
