K2-18 b: A New Hope for Alien Life?
Agencies
Islamabad: In a groundbreaking astronomical development, scientists using the James Webb Space Telescope (JWST) have discovered the strongest evidence yet of potential life beyond Earth. Researchers have detected in the atmosphere of an exoplanet named K2-18 b chemical signatures of gases that, on Earth, are produced exclusively by living organisms.
The gases in question—dimethyl sulfide (DMS) and dimethyl disulfide (DMDS)—are known biosignatures, typically generated by marine phytoplankton and other microbial life forms on Earth. Their presence in the atmosphere of K2-18 b, a planet orbiting a distant star 124 light-years away in the constellation Leo, has raised hopes that this world may be teeming with microbial life.
However, scientists are treading carefully. “We are not claiming to have found actual life,” said astrophysicist Dr. Nikku Madhusudhan of the University of Cambridge and lead author of the study published in The Astrophysical Journal Letters. “These are signs of a possible biological process, not living organisms.”
Still, the findings mark a major step forward in the search for extraterrestrial life. “This is a transformational moment,” Madhusudhan said. “We have shown that it is possible to detect potential biosignatures on habitable-zone exoplanets using current technology. We’ve entered the era of observational astrobiology.”
A ‘Hycean World’
K2-18 b, classified as a sub-Neptune, is about 8.6 times more massive than Earth and 2.6 times larger in diameter. It resides within the habitable zone of a red dwarf star—where temperatures could allow for liquid water, an essential ingredient for life.
Scientists believe the planet may be a “hycean world”—a type of exoplanet theorized to have vast oceans of liquid water and a hydrogen-rich atmosphere, making it potentially suitable for microbial life.
Webb’s earlier observations of K2-18 b revealed methane and carbon dioxide in the atmosphere—carbon-based compounds that are critical for life as we know it. Now, the detection of DMS and DMDS at concentrations far higher than those found on Earth adds new weight to the hypothesis of biological activity.
“These gases are present at more than 10 parts per million, thousands of times higher than in Earth’s atmosphere,” said Madhusudhan. “Based on current knowledge, such high levels cannot be explained without biological activity.”
Cautious Optimism
The researchers detected the atmospheric gases using the transit method, which analyzes starlight as it filters through a planet’s atmosphere during orbit. This method allows scientists to identify the molecular composition of the planet’s atmosphere from Earth.
The study reports a 99.7% confidence level in detecting DMS or DMDS, meaning there is still a 0.3% chance the results are a statistical fluke. To reach the level of scientific certainty required to confirm life—less than a one-in-a-million chance of error—further observations and validation are needed.
Madhusudhan emphasized the importance of skepticism and further investigation. “We must repeat the observations and explore every possible non-biological explanation for the findings,” he said. “Even though DMS and DMDS have been considered strong biosignatures, it’s crucial to rule out any abiotic sources.”
Other scientists agree. Dr. Christopher Glein of the Southwest Research Institute, who was not involved in the study, called the findings “tantalizing,” but urged rigorous scrutiny. “This is an exciting development, but we must be cautious. Independent analyses and further research will be essential in the coming weeks and months.”
The Quest Continues
More than 5,800 exoplanets have been discovered since the 1990s, but K2-18 b is now among the most compelling candidates in the search for alien life. The Webb telescope, operational since 2022, has significantly advanced the field by allowing detailed analysis of exoplanetary atmospheres.
While the current findings point toward possible microbial life, scientists remain uncertain about the presence of more complex life forms. “We’re likely talking about simple life, similar to what we find in Earth’s oceans,” said Madhusudhan. “The question of multicellular or intelligent life is far beyond our current capabilities to answer.”
Despite the cautious tone, this discovery brings humanity a step closer to answering one of its oldest questions: Are we alone in the universe?
“We might be just a few years away from finding an alien world that harbors life,” Madhusudhan concluded. “But for now, we must follow the science—patiently and thoroughly.”
