Alien life has been on the minds of humans for hundreds of years — now, scientists believe they are one step closer to finding it.
In recent years, researchers have focused on studying exoplanets, planets that orbit stars outside the Solar System.
They are extremely far away, though many are believed to be home to vast oceans.
Searching for these oceans is no easy feat, and can take years.
The pay-off is rewarding, however, and a new study proposes a way to identify these exoplanets more efficiently — and potentially find alien life along the way.
Scientists have so far discovered over 5,000 exoplanets, though it has been exceedingly difficult to confirm the presence of water.
While water vapour is often detected, pinpointing the source of that water vapour is an altogether different story.
A new paper published in the journal Nature Astronomy by researchers at the University of Birmingham suggests that “atmospheric CO2 levels hold the key to finding habitable planets and potentially life itself”.
The Earth’s oceans absorb a huge portion of atmospheric CO2, and so the scientists sat an exoplanet with lower CO2 levels that its neighbours could well be hiding a liquid ocean beneath its surface.
“We know that initially, the Earth’s atmosphere used to be mostly CO2, but then the carbon dissolved into the ocean and made the planet able to support life for the last four billion years or so,” wrote study co-lead author Amaury Triaud, professor of exoplanetology at the University of Birmingham in the UK.
Because CO2 absorbs infrared radiation, scientists can use NASA’s James Webb Space Telescope (JWST) to search for the vital indicator. Using the telescope for this is possibly the best way to find it, as CO2 is an especially strong infrared light absorber, and is easy to detect.
“It’s a really nice way of doing this,” said Sarah Casewell, a lecturer in the School of Physics and Astronomy at the University of Leicester who wasn’t involved in the research.
“And it’s also not going to involve a massive investment of telescope time, which is really important because that’s extremely precious to our community.”
Ultimately, if successful, the technique could find signs of alien life on distant planets.
There is an additional indicator that although doesn’t fully prove the existence of life at least hints at it: low carbon levels.
Carbon is an organic molecule that is crucial to the building blocks of life. The team believe that the combination of CO2 and the presence of an ozone layer in an exoplanet might not mean only microbial life forms but, at least hypothetically, a planet alive with organisms.
“Life on Earth is planet-shaping,” the researchers wrote. “Planet-shaping life is really what astronomers are after.”
