In a survey taken after the K2-18b announcement, just 6.6% of astrobiologists said they believed scientists had probably detected extraterrestrial life. Close to two-thirds rejected the idea entirely.
The real story is that distance between the headlines and the researchers who do this work for a living — and it is the part hardly anyone covered.
From the outside, after all, 2025 had the look of the year we finally got close. One press release announced the “strongest hints yet” of extraterrestrial life on the exoplanet K2-18b. Several months on, speaking about a sample taken from a Martian rock named “Cheyava Falls”, NASA Administrator Sean Duffy called it the “closest we have ever come” to finding life on the red planet.
Nobody ever tallies the room
There is something strange about the route science takes to reach you. Whenever a breakthrough or a controversy dominates the news cycle, journalists and press officers reach for a handful of experts. What those experts say can be incisive and genuinely useful. What it almost never does is capture the view of the broader research community.
Meanwhile, public debate leans again and again on phrases like “the science says” or “scientists believe” — as though someone had gone and counted.
Almost always, no one has. Hard evidence about what scientists collectively think is largely absent. My colleagues and I set out to close that gap in astrobiology, polling hundreds of astrobiologists drawn from the international research community within days of each of the two major 2025 announcements. The question we put to them was simple: did they think extraterrestrial life had probably been discovered?
Two announcements, two very different responses
K2-18b came first. Researchers reported in April 2025 that they may have spotted molecules called dimethyl sulfide and/or dimethyl disulfide. Here on Earth, both are linked to biological activity. The coverage was intense, and much of it cast the finding as a remarkable leap forward in the hunt for alien life.
The second arrived in September, with NASA’s announcement that Cheyava Falls seemed to hold a potential biosignature. Those so-called “leopard spots” are mineral rings that, on Earth, frequently result from microbial activity. Once again the headlines ran hot — and so did NASA’s own officials.
The survey results never matched that noise. On K2-18b, 6.6% agreed, almost two-thirds disagreed and 28.0% remained neutral. For Mars, confidence rose but stayed cautious: agreement reached 15.1%, disagreement fell to 44.6% and neutrality rose to 40.3%.
The figure that shows what really moved
Look only at the agree and disagree columns and the actual shift passes you by.
What collapsed was strong disagreement — from 35.1% on K2-18b down to 11.1% on Mars. Very little of that movement was rejection converting into endorsement. Mostly it was firm rejection softening into something far more provisional.
Expert opinion shifted, then, but the shift had structure. The community grew more receptive to the possibility without ever committing to it.
Some of that likely comes down to the nature of the evidence. K2-18b hinged on possible atmospheric signatures detected across interstellar distances. Mars offered a rock that can be examined directly and in vastly greater detail. Astrobiologists have also understood for decades that lifelike features can emerge from processes with nothing biological about them. The difficulty is rarely in picturing how life might generate a signal; it lies in ruling out every route by which nature could counterfeit one.
Five answers, not two
Public conversation tends to treat a scientific community like a switch — it either agrees or it doesn’t. But the distribution carries just as much weight. Strong agreement, agreement, neutrality, disagreement and strong disagreement each reveal something distinct about how a field is digesting a claim.
A large neutral bloc can carry several meanings simultaneously. Researchers might regard the evidence as genuinely inconclusive. They might hold some intermediate level of confidence. Or they might consider a claim too speculative to back or dismiss. A move from strong disagreement to plain disagreement can indicate softening even when overall disagreement remains high. Compress all of that into “for” or “against” and the information disappears.
This was never really about aliens
The identical problem crops up in climate science, in pandemics, in artificial intelligence and in medical research — all fields where public discussion reaches for scientific consensus at every turn.
That consensus is sometimes genuine. Sometimes it is not. In either case, we seldom possess any systematic means of measuring what scientists actually believe, least of all where the evidence is still emerging or the uncertainty runs deep. Into that vacuum step selective quotation, the loudest voices and guesswork about what everybody else thinks.
That is beginning to shift. Our research group at Durham University — C-Scope, the Centre for Scientific Community Opinion Polling and Evaluation — examines how expert opinion is distributed and how it changes over time. We have no interest in substituting polling for evidence, and we do not equate majority opinion with truth. The aim is to understand how scientific communities cope with uncertainty.
Science moves forward through uncertainty, disagreement and gradual revision. So when the next press release assures you we have never been closer, put a sharper question to it: closer in whose judgement, and how many of them hold it? For K2-18b, that answer came to 6.6%.