Astronomers claim strongest proof of foreign life yet

Astronomers claim to have seen the strong evidence so far for life on another planet. But other astronomers have called for tied entity for the conclusions to be verified by other groups, and alternative, non-biological explanations can be excluded.

“These are the first tips we see of a foreign world that may have been inhabited,” Nikku Madhusudhan told the University of Cambridge to a press conference on March 15.

Astronomers first discovered exoplanet K2-18B in 2015 and soon found that it was a promising place to look for life. About eight times as massive as earth and orbit over a star 124 light years away from us, the planet sits in the habitable zone of its star where liquid water can exist. Further observations found evidence of water vapor in 2019, which led to suggestions that the planet may be covered by oceans sitting under a hydrogen atmosphere but not all astronomers agreed.

In 2023, Madhusudhan and his colleagues use the instruments on James Webb Space Telescope (JWST) to look at K2-18B’s atmosphere in almost infrared light and found again proof of water vapor as well as carbon dioxide and methane. But they also found a tempting hint of dimthylsulfide (DMS), a molecule produced on earth only by living organizations, Handly Marin phytoplankton. However, the signs for DMS were extremely weak, and many astronomers claimed that we need very strong evidence to be sure of the presence of the molecule.

Now Madhusudhan and his colleagues have used another instrument from JWST, the middle infrared camera, to observe K2-18B. They found a much stronger signal for DMs as well as a possible related molecule called Dimthyl Disulfide (DMDs), which is also produced on Earth only by life.

“What we find is an independent line of proof in another wavelength area with another instrument with possible biological activity on the planet,” said Madhusudhan.

The team claims that the detection of DMS and DMDs is at the three-Sigma level of statistical significance, which corresponds to a 3-in-1000 chance that a pattern of data like this will end up becoming a fluke. In physics, the standard limit for accepting something as a true discovery is five Sigma, which is equivalent to a 1-in-3.5 million chance that the data is a chance.

Nicholas Wogan at the NASA Ames Research Center in California says the evidence is more compelling than the 2023 results, but it still has to be verified by other groups. Once the data is published next week, other researchers may begin to confirm the conclusions, but this may take weeks or months due to the difficulty of interpreting JWST data. “It’s not just as if you are downloading the data and you see if there are DMS – this is this super -complied process,” says Wogan.

Other researchers are more skeptical of the conclusions. “These new JWST observations did not offer compelling proof that DMS or DMDs are present in K2-18B’s atmosphere,” says Ryan Macdonald at the University of Michigan. “We have a boy-with-credit wolf situation for K2-18B, where several previous three-Sigma detections are completely horizontal when they are subject to closer voters.

Madhusudhan and his team estimate that between 16 and 24 hours of additional observations with JWST could help them reach the Five-Sigma level, but the difficulty of observing the planet’s atmosphere means they can’t guarantee this.

“The relative size of the atmosphere compared to the size of the planet is pretty close to the thickness of an apple skin on top of an apple. That’s what we’re trying to measure,” says Thomas Beatty at the University of Wisconsin-Madison, who was not part of the study team. Wogan adds that getting to five Sigma may be fandamentally impossible for the love of noise in the data.

But if further observations can be that this is a real discovery, it would be a “huge progress,” Beatty says. “To ignore it or not, it’s actually produced by life for a moment, it’s something that people said a decade ago would be proof of life in the atmosphere of a planet that could host it.”

Madhusudhan and his colleagues calculate the possible concentrations of DMS and DMDs on K2-18B appear to be 10 parts per day. Million, thousands of times greater than the concentrations in the Earth’s atmosphere. This may indicate a much greater amvent in biological activity than on Earth if the signal turns out to be correct, but noting that the chemicals have a biological origin will take more work, he says.

“We have to be extremely careful,” Madhusudhan said. “We cannot claim on this internship that even though we discover DMs and DMDs that it is due to life. Let me be very aware of it if you take published studies so far, there is no mechanism that can explain what we see.

To exclude alternative Méchanisms could take some time, says Wogan. “Something like this has not really been examined. DMS in a hydrogen -rich atmosphere, we don’t know a ton about it. There should be a lot of work.”

The difficulty of proving that it could not have a non-biological explanation could put K2-18B in the category of a viable biosignature candidates for a long time, says Sara Seager at the Massachusetts Institute of Technology. “It may remain in this category for decades, as the question may never be fully resolved with the limited data offered,” she says.

However, Madhusudhan says that the finding is an important appearance of where the chambers of life or not. “This is a revolutionary moment, fundamental to me astronomer, but also to our species – that we have been able to come from a single cellular life, billions of years ago, to an advanced technological civilization capable of looking through the atmosphere of another planet and news activity,” he said.

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