In the search for life in the universe there have been plenty of close calls. Each instance brings us closer to answering that existential question and lays bare how we as humans may react to such a revelation. In this episode, we’ll take a look at those close calls.
We begin in Cambridge, England, in 1967, where a graduate student by the name of Jocelyn Bell Burnell is working on a brand new radio telescope. She’s on the hunt for quasars – these mysterious and powerful bursts of energy in the cosmos.
“They were the really hot, sexy topic at that time and very new,” she told me during an interview in March 2020.
We talked about that hunt for quasars and how it led her to something completely unexpected.
“It was a string of pulses, about one and one-third seconds apart, so it was going - dit - dit - dit - dit - dit - which suspiciously like some man – a human being – doing something,” she said.
Was someone out there signaling Earth? Did Bell Burnell finally find what Frank Drake was listening for? In less than a decade was the question of are we alone already answered?
What Bell Burnell found was groundbreaking, and just one of many times we thought we had that answer to whether or not we were alone in the universe.
Little Green Men
Emma Chapman is an astrophysicist at the University of Nottingham in England. She uses radio telescopes in her work to look at the cosmic dawn, the first signs of our universe’s formation. But she also combs through historical astronomical data looking for signals that might be from some other civilization — sent to us on purpose or on accident.
And it was that kind of data that Bell Burnell stumbled upon some 60 years ago.
“She was looking for all this data in her printouts that were coming from this radio telescope,” Chapman explained of Bell Burnell’s work.
Bell Burnell was looking through a scroll of chart paper that measured cosmic radio intensity much like a cardiac ECG does. In a football field’s length of this chart paper she found what she described as “a little bit of scruff” of a repeating signal.
“They ended up saying, ‘is this repeating signal coming from this one place in the sky? Could it be little green men, you know?’ And they wrote LGM,” said Chapman.
“‘Maybe it's aliens’ is a bit of a catchphrase in astronomy,” she said. “That's where it began.”
But it wasn’t aliens. That dit - dit - dit - dit - that Bell Burnell saw in that data showed up again and again.
“Very quickly they actually realized that they had spotted two or three more in different areas of the sky,” said Chapman. “Now the chances of aliens contacting you all at the same time from three or four different completely remote places in the universe is vanishingly small.”
It was a false alarm. But the finding wasn’t a bust. Instead, she found evidence of what are now called pulsars — cosmic lighthouses of energy – a neutron star that spins rapidly emitting beams of radiation.
The discovery wasn’t evidence of intelligent life. But it was profound enough to earn a Nobel Prize in 1974. Controversially, though, not for Bell Burnell.
The finding is just the first of many false alarms that clue us in to just how the world might react to the day we find the real thing, and those findings happened much closer to home than we ever expected.
Life in a Mars rock?
On August 7, 1996, President Bill Clinton addressed reporters on the South Lawn of the White House.
“Today, rock 840001 speaks to us across all those billions of years and millions of miles. It speaks to the possibility of life,” he said. “If this discovery is confirmed, it will surely be one of the most stunning insights into our universe that science has ever uncovered.”
Scientists found what they thought was microbial evidence of life in a 4.5 billion-year-old meteorite found in the Allan Hills in Antarctica in 1984. It was a chunk of Mars that broke off and found its way to Earth, and trapped within it, some scientists thought, evidence of life from another planet.
Amy Williams is an astrobiologist at the University of Florida and a scientist on NASA’s Curiosity and Perseverance rovers — which are currently searching for evidence of life on Mars now.
“This meteorite was being studied by a group at Johnson Space Center, and as they continue to study it, they found what they argued were multiple lines of geochemical evidence that came together,” she said. “ They said the most parsimonious explanation would be that this could be life – a form of preserved life in this meteorite.”
The team was led by NASA scientist David S. McKay. But as other scientists took a closer look at the findings, they disagreed with the initial conclusion.
“I would say the community generally [finds the] consensus is no, you don't have evidence for ancient Martian life in this meteorite,” she said. “But this discovery and the conversation that it started is truly the birthplace of modern astrobiology."
Astrobiology is the scientific study of the origin, evolution, distribution, and future of life in the universe. Simply put, it studies whether there is life in the universe.
While the findings from that meteorite didn’t answer that question, it got scientists closer to an answer. President Clinton charged NASA with exploring Mars further.
Later that year, the Mars Global Surveyor mission launched, and in 1997, NASA’s Mars Pathfinder landed on the red planet. While those missions were already underway, the publicity from the now-debunked findings no doubt propelled the search for life into a new era.
“People still walk around remembering this meteorite paper. I see it serving both [the] good and negative sides of science education and communicating with the public,” she said. “It’s really great that it launched astrobiology. It lays bare the challenges and flaws inherent in the scientific method. We're not always right. That's why we test hypotheses."
And those hypotheses would be tested again and again on planets other than Mars.
A mysterious gas on Venus
In September 2020, a team of astronomers announced the finding of phosphene gas in the upper atmosphere of Venus.
Phosphene is a colorless gas. Here on Earth, it’s created by decaying organisms – what was once life.
Venus is known as Earth’s twin. It’s similar to our planet in size, mass, and structure — it’s rocky, like ours. But what is on the surface is far from Earth. It’s a toxic inferno with a thick carbon dioxide atmosphere. It’s hot enough to melt lead.
So why is phosphene detected on Venus?
Phosphine is pretty common in things like giant planets, and there's a bunch of mechanisms we think that might produce it, but it is exceedingly rare in smaller rocky worlds like Venus, and on Earth,” said Paul Byrne, a planetary scientist at Washington University in St. Louis.”
There is going to be a lot of scrutiny, and that's how it should be. That is the scientific method.Paul Byrne, Planetary scientists
Phosphine, as we know it, is exclusively linked to life, found in places like bogs and swamps from the organic breakdown by bacteria. A finding of phosphene in Venus points to the possibility of life within its atmosphere.
“This phosphine detection really was stunning, and the team went through great lengths to first off demonstrate the robustness of their detection, and then to offer explanations that might account for why there might be phosphine there,” Byrne said. “And what they felt was that there really wasn't much they could rule in, except perhaps some kind of weird biology.”
Was that weird biology alien life? The findings captured the attention of the media and other scientists who worked to confirm what they found. Follow-up studies challenged whether the team detected the phosphene signal at all, and the original researchers revised their estimate of just how much phosphene there was.
Now, whether the findings are an indication of life are still up in the air.
“Like anything, when we detect the potential trace of a gas we might not expect in the atmosphere of a planet, whether this system or beyond, there is going to be a lot of scrutiny, and that's how it should be,” said Byrne. “That is the scientific method."
But sometimes public interest outweighs scientific merit.
“Why the hell didn’t you come by?”
“Are aliens headed for Earth, right now?” asked one news anchor in October 2025. He was referring to a news story about 3I/Atlas, a comet that originated beyond our solar system that would pass by Earth – although it posed no threat.
It was discovered in July that year and is the third known interstellar object to travel through our solar system.
“It's a comet that came in at such high speed that it can only have been on an orbit kind of way out of our solar system's reaches,” said Chapman.
Some in the science community thought it might be alien technology – a beacon or interstellar spacecraft.
But the science community overwhelmingly argued it wasn’t from an alien civilization. Despite that, the comet continued to capture headlines and social media posts. It brought the search for life into the mainstream — even just briefly — and put attention to the skies and that question: are we alone? Is someone coming to say hello?
The scientific community turned its eyes to the comet as it made its closest flyby in December 2025, taking careful observations to see if it might be some sort of alien technology, a beacon, or interstellar spacecraft.
It wasn’t. And neither were the two that came before it.
“From what we believe and observe and have understood about these — no, they were not in fact engineered, that they were natural objects,” said Bill Diamond, President and CEO of the SETI Institute.
“Yes, it was disappointing,” he said. “It would have been amazing if it was a spacecraft, except I would then say, if you're a spacecraft, why the hell didn't you come by? If you came all that way, it'd be kind of a shame to miss us.”
The interstellar visitor – and the media attention it garnered – shows a gap between what some call scientific nonsense and public interest, said York University anthropologist Katheryn Denning.
“It's so important in those cases to acknowledge that the scientific community at large is pretty darn clear on what those objects are or were, and what they are not,” she said. “But it's a really interesting example in how the larger scientific consensus does not necessarily carry the day in terms of public opinion."
But there’s still one longstanding false alarm that still doesn’t have consensus as to what it actually is.
The “Wow!” signal
The Big Ear telescope at Ohio State University was massive. It was three football fields wide and from 1973 to 1995, its job was to listen for extraterrestrial radio signals.
“In 1977 they got an incredibly strong burst of radio light,” said Chapman. “Now, this is one of the brightest radio signals we've ever received, and the astronomer who was combing through the data at the time saw this really high intensity burst, and wrote "wow" with an exclamation mark in the margins of that data.”
The “Wow!” signal. It’s a computer printout with a bunch of printed numbers. But a series of numbers and letters is circled in red ink with that word Wow written in the margin. Radio telescopes collect radio waves that are traveling through space. Using massive dishes, they listen for these waves, then turn them into numbers or letters that represent the intensity and frequency of the waves.
Radio telescopes collect radio waves that are traveling through space. Using massive dishes, they listen for these waves, then turn them into numbers or letters that represent the intensity and frequency of the waves. Chapman explains these printouts look a lot like a scene from the movie The Matrix.
“Like the kind of like the green numbers falling down the screen,” she tells me. “That's what the data looks like in 1977. Imagine as if somebody was printing out the matrix numbers falling down, so it's loads of different numbers and letters all coming down, and the higher those numbers – they went from one to nine – to higher intensity.”
If the intensity got beyond nine, the computer would switch to letters, starting with A then moving to Z as the highest. The “Wow!” signal observation got as high as Q.
“They never had anything like that,” said Chapman.
The signal was so bright, and lasted for over a minute. Then it vanished.
Had it been a natural phenomenon — like Jocelyn Bell Burnell’s pulsars — you’d expect to see it again and again. But it was a single burst. A signal flair, perhaps. And it was never seen again.
“I’m not saying there was an alien with a green finger literally turning it off, but something really strange happened.”
Chapman is puzzled by the fact that after the signal, there was very little scientific attention. It was treated more as gossip than a scientific finding. But recently, within the past decade or so, there’s been more follow up.
“We don't know it's a false alarm,” she said. “What the “Wow!” signal is, is one of the few times in human history that we have heard what appears to have all of the characteristics of an extraterrestrial radio signal.”
The false alarms we’ve been talking about in this podcast are just a handful of the dozens that we’ve discovered over the years. But for decades, the “Wow!” signal has continued to puzzle scientists.
We’re still not sure it was a false alarm. What could it be?
“Am I saying it's definitely aliens? Just to be clear, absolutely not. I'm saying we are still in the trenches of science with this one,” Chapman said. “We are still trying to work out what it is, and we do not know."
