A team of researchers led by University of Cambridge astronomer Nikku Madhusudhan has detected promising biosignatures in the atmosphere of K2-18b, a distant planet 120 light-years from Earth. The findings, published in The Astrophysical Journal Letters, indicate the presence of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) gases, which are also produced on Earth by marine phytoplankton.
The discovery was made using NASA’s JWST telescope, which observed the signature of these gases in starlight that had passed through K2-18b’s atmosphere. The team’s results will likely spark interest in the planet’s potential for life, but caution is needed due to concerns about instrument artifacts and alternative explanations for the detected signals.
K2-18b itself is an unlikely candidate for extraterrestrial life due to its vastly different composition from Earth. The planet’s size and mass are similar to those of gas giants like Neptune, rather than rocky planets like our own. However, previous studies have suggested that K2-18b could have habitable conditions on its surface, with some researchers even proposing the existence of a “hycean” world – a thick atmosphere dominated by hydrogen.
The recent discovery of DMS in K2-18b’s atmosphere was met with skepticism last year when a similar signal was detected in the comet 67P/Churyumov-Gerasimenko. However, Madhusudhan’s team now reports a stronger DMS signal, as well as possible traces of DMDS.
While the detection is intriguing, researchers emphasize that it is just one piece of evidence and not conclusive proof of life on K2-18b. To confirm the presence of life, more thorough knowledge of the planet’s atmosphere and surface is needed to rule out alternative explanations.
“This signal is incredibly tenuous,” says Oliver Shorttle of Cambridge. “We need to read everything we can from these tiny amounts of light.” Catherine Heymans of the University of Edinburgh notes that even with perfect data, it’s impossible to say for sure if DMS on an alien world is of biological origin due to geological activity.
The scientific community remains divided on the implications of the discovery. Some researchers remain skeptical until more evidence emerges, while others see this as a promising lead in the search for extraterrestrial life.
Source: https://www.science.org/content/article/alien-planet-s-atmosphere-bears-chemical-hints-life-astronomers-claim