Scientists are optimistic about detecting life signs on another planet. NASA's James Webb Space Telescope recently detected hints at life on a planet outside our Solar System. The space telescope found a possible sign of gas that is produced by simple marine organisms detected in the atmosphere of a planet named K2-18b, which is 120 light years away.
"We live in an infinite Universe, with infinite stars and planets. And it's been obvious to many of us that we can't be the only intelligent life out there," says Prof Catherine Heymans, Scotland's Astronomer Royal told BBC.
"We now have the technology and the capability to answer the question of whether we are alone in the cosmos."
Webb's discovery adds to recent studies suggesting that K2-18 b could be a Hycean exoplanet, one which has the potential to possess a hydrogen-rich atmosphere and a water ocean-covered surface, NASA said in a press release.
K2-18 b orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth in the constellation Leo. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our solar system. This lack of equivalent nearby planets means that these 'sub-Neptunes' are poorly understood, and the nature of their atmospheres is a matter of active debate among astronomers.
"Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere," explained Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper announcing these results. "Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations."
NASA said that the abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be a water ocean underneath a hydrogen-rich atmosphere in K2-18 b. These initial Webb observations also provided a possible detection of a molecule called dimethyl sulfide (DMS). On Earth, this is only produced by life. The bulk of the DMS in Earth's atmosphere is emitted from phytoplankton in marine environments.
The researchers will confirm in a year's time whether the hints are confirmed or have gone away.
If the team do not find life signs on K2-18b, they will study 10 more Goldilocks planets. Prof Madhusudhan said even finding nothing could provide "important insights into the possibility of life on such planets".
