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The big astrophysics news last week, ending on the 18th of April, 2025 was that, while studying an exoplanet called K2-18b, researchers MAY have identified dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the exoplanet’s atmosphere—molecules that, on Earth, are only produced by living organisms, primarily marine phytoplankton.

This has driven people to make all sorts of claims about strong evidence of life existing on the exoplanet. For example, the BBC had the following headline, i.e., “Scientists find ‘strongest evidence yet’ of life on distant planet”, while the Planetary Society had the following headline, i.e., “A possible sign of life on K2-18b? Here’s what it means — and why it’s just the beginning”. The CNN on its part had the following story, i.e., “Scientists detect signature of life on a distant planet, study suggests”.

The common thread in these stories was that the claimed detection of DMS and DMDS was a sign that there could be life on the exoplanet K2-18b.

Of course, caution needs to be taken before making definite claims. There are several reasons for this:-

Firstly, while scientists have detected possible traces of DMS and DMDS in the atmosphere of K2-18b, the findings are still under scrutiny. The detection reached a three-sigma level of statistical significance, meaning there’s a 0.3% probability that the signal appeared by chance. However, the gold standard for scientific confirmation is five-sigma, which would reduce the probability of error to an extremely low level.

Secondly, it should also be remembered that traces of DMS have been detected on a comet, suggesting that it can be produced through non-biological processes.

Thirdly, the distance to K2-18b is about 124 light years, meaning that light would take some 124 years to travel to K2-18b. With our current technology, our fastest space craft would take about 1.68 million years to cover that distance. So, we are not visiting the exoplanet anytime soon to physically confirm the existence of life on the exoplanet. We will definitely need more than the detection of DMS and DMDS to finally determine if life exists on the exoplanet.

So, as exciting as the news of the possible detection of DMS and DMDS may be, there is still a lot that needs to be done, before we can make any claims of existence of life or lack thereof on the exoplanet.