For as long as humans have been on Earth, we have looked up to the sky and wondered if there might be other life out there. Today, scientists may begin to answer that question.
In a recent paper published in the Astrophysical Journal Letters, Dr. Nikku Madhusudhan and his team at the University of Cambridge claim to have found evidence of a molecule in the atmosphere of an exoplanet which could indicate the presence of microscopic life.
The exoplanet in question, K2-18b, is located approximately 124 light-years from our sun, and orbits within the habitable zone of its star, meaning liquid water is thought to be possible on its surface. In fact, some scientists believe that K2-18b is what is known as a “hycean world,” meaning it is covered with an ocean under a thick hydrogen atmosphere.
Photo by NASA.
The prospect of K2-18b having a water ocean is what has made this recent discovery all the more interesting. Using specialized equipment aboard the James Webb Space Telescope (JWST), Madhusudhan and his team claim to have found evidence of dimethyl sulfide (DMS), a molecule which here on Earth, is only produced by living organisms.
It must be stated that there is still considerable uncertainty about exactly what has been found. According to the team who made the discovery, “More observations are needed to increase the robustness of the findings.”
Assuming DMS has in fact been discovered in the atmosphere of K2-18b, what does this mean?
As stated, there are very few known ways of creating DMS without the presence of biological life. That is not to say there are no known ways, but the quantity that Madhusudhan and the researchers claim to have found cannot be explained by known processes.
“The amount we estimate of this gas in the atmosphere is thousands of times higher than what we have on Earth,” according to Madhusudhan. “So, if the association with life is real, then this planet will be teeming with life.”
Photo by University of Rhode Island / Stephanie Anderson.
That being said, this is an alien planet orbiting a different star from us, with an atmospheric composition completely different from that of Earth. It is entirely possible that there are unknown geologic or atmospheric processes that could result in the amount of DMS observed.
Ultimately, it is now the time for more science. While far from conclusive evidence of life, the data gathered about K2-18b has made it by far the most interesting exoplanet we have yet discovered. As more data is collected using the instruments on JWST and other advanced telescopes, scientists may one day be able to reach a consensus on whether K2-18b is “teeming with life.”
Assuming that is the path things take, we may look back at this moment as the first time we discovered evidence of life outside of Earth. The implications of this could be massive. If life managed to evolve separately around two stars only 124 light-years apart, that bodes well for the commonality of life across the galaxy.