Sometimes it amazes me how quickly science advances.

Just over thirty years ago there were no known exoplanets, and some astrophysicists were even speculating on whether they ever would be detected. Then in the early 1990s, multiple teams of astronomers were able to detect the periodic dimming of distant stars, and later the Doppler shift in the light from other stars, and from that data they were able to conclusively prove the existence of exoplanets. Now there are several thousand known planets in other stellar systems, and the variety and nature of the planets has stunned even the most imaginative astronomers.

And now we have (possibly) another major advance in the study of exoplanets. This week a team of scientists used data from the James Webb telescope to detect a strong indication of life on a planet 120 lightyears away.

Planet K2-18b is a planet orbiting red dwarf star in the Leo constellation, believed to be about eight and a half times as massive of the Earth, and it has been making news for several years and many reasons.

In 2019 astronomers studied the spectrum of light from the red dwarf as it passed through the atmosphere of K2-18b, and using that spectral data they were able to detect the presence of water vapour on the planet. This was obviously very exciting news at the time, because on Earth, everywhere that liquid water exists (and thus water vapour) we know that there exists some form of life. So detecting water vapour in the atmosphere of another world was an indicator that it could also be home to some form of alien life.

As a result, astronomers started focusing more telescope time and data analysis on this distant planet. Further study resulted in some debate on whether the initial detection was water or methane, but also proved the existence of carbon dioxide in the K2-18b atmosphere. 

So our best guess now is that K2-18b is a massive planet that has liquid water on the surface and a hydrogen rich atmosphere that includes organic molecules containing carbon. It would seem to have all of the ingredients necessary to produce life similar to our own terrestrial biology.

And the result announced this week has added further interest to this exoplanet.

The latest observation by the James Webb telescope have revealed the presence of dimethyl sulphide in the atmosphere. On Earth, this substance is really only produced naturally by phytoplankton in the oceans. There are other reactions that can produce it, but on our own planet they don't occur in significant amounts outside of the laboratory. If this is also true of K2-18b, then it would prove that that planet also houses some form of comparable carbon based life.

Of course there are also several caveats that must be added here. NASA themselves are quick to add that the detection of dimethyl sulphide is significantly weaker than the other observations, and could still be proven to be a statistical anomaly or a detection error. They might not have observed it at all. It must also be noted that connecting this observation to life is based on what we know of our own ecosystem, but there is no reason to assume that a planet more than a hundred light years away follows the same laws of nature. Perhaps it simply contains an environment that produces chemical reactions not seen on Earth, but not related to biological life forms either.

And of course for the sci-fi fans, it is also worth noting that there is a significant difference between the discovery of plankton in a distant ocean and the possibility of an advanced civilizations of intelligent beings!

For now it is an interesting result, but one that will need more extensive observations before any definitive interpretations can be made. Whether the JWT has actually detected dimethyl sulphide will require much more study, and even more observations will be required to state that K2-18b has life on it.

But it is still fun to imagine where this result will lead in the years and decades to come...