One night a few years back I had a late night call from a friend who was involved in Breakthrough Starshot, the attempt to design a probe that could reach nearby stars and return data with transit times of decades rather than centuries. His news was surprising. The Parkes radio dish in Australia, then being used by the Breakthrough Listen SETI project, had detected a signal that seemed to come from Proxima Centauri. “What’s interesting,” said he, “is that when you move the dish off Proxima, the signal disappears.” You probably remember this episode, which had a brief moment in the news and may well live on among the conspiracy-minded in the wackier regions of cyberspace.
We know now that the signal was some form of radio frequency interference, commonly abbreviated RFI. In any case, our conversation was relatively tame because the idea of a terrestrial explanation seemed inevitable, no matter how tantalizing the first look at this signal. After all, with all the years of SETI effort since the original Project Ozma, was it likely that we would pick up a signal from the nearest of all stars? What were the odds that there would be a radio-using civilization so close to home?
Here I’m being deliberately provocative, because in fact we couldn’t know the odds. We know absolutely nothing about alien civilizations including whether or not they exist. To go science fictional, suppose Earth had triggered a nearby ‘lurker’ probe that had been in our Solar System monitoring our activities and had learned about our interest in the Alpha Centauri system. Would they possibly use a signal from Proxima as an introduction to first contact? Maybe from a lurker probe in that system? The scenarios can get as wild as anyone might wish. Best, then, to keep an eye on that signal.
It’s instructive to see what happened following the Proxima ‘detection,’ which occurred on April 29, 2019, and I’m reminded of it by Chris Lintott’s fine new book Accidental Astronomy (Basic Books, 2024). An astrophysicist at Oxford and well known television presenter for the BBC program ‘Sky at Night,’ Lintott writes with his usual grace about the often serendipitous way astronomical discoveries happen, from the appearance of ‘Oumuamua to the surprises Cassini found at Enceladus. The overall point is that you have to look to find something, and in astronomy keeping the lenses pointed without preconceptions often churns up something rare and strange.
So what was interesting about the April 29, 2019 event? One eye-catching thing was that the radio signature was extremely narrow, an interesting fact given that naturally emitted radio waves tend to cover a wide range of wavelengths. Narrow-band signals are the kind of thing we think of as the stuff of radio broadcasts. In other words, technologies. I mentioned that the signal disappeared when the Parkes dish was moved off Proxima, and it also reappeared when the dish was returned to the target. This process, known as ‘nodding,’ is a handy way to rule out background radio sources.
So the signal definitely had the attention of the scientists at Breakthrough Listen, who dubbed it BLC1 (Breakthrough Listen Candidate 1). It also seemed to show a Doppler effect, changing in frequency slightly as time passed in ways that would be expected for a transmitter on a planet orbiting a star. If you think back to the famous ‘Wow!” signal of August 1977, detected at the Big Ear radio telescope run by Ohio State University, you can place it and BLC1 in context. The key is to look for signals that are narrowband, and if they repeat, so much the better. The Wow! Signal didn’t repeat, but BLC1 showed up more than once in 2019.
After that, the repetitions ceased, with no appearances in the following years. Now what? Transmissions from Earth satellites were ruled out given their much greater frequency drift, and deep space probes like the Voyagers and New Horizons were not aligned to match the Proxima signal. At this point scientists were turning over rarer and rarer explanations, including a transmitter on an asteroid, or an Earth-based transmitter that was deliberately being used to mimic a legitimate SETI signal. None of this fit BLC1, which in any case tracked Proxima’s motion across the sky.
The problem with anomalies like this one is that they go up in smoke if similar events occur with mundane explanations. When analyzed more closely, the Parkes data from the relevant period between April and May of 2019 contained four new detections of BLC1. But they also contained the same signal some fifteen times during periods in which the telescope was not pointing at Proxima. And at least one of these detections persisted as the telescope moved on and then off the target, which ruled out a signal from an alien civilization and pointed to an explanation much closer to home.
Looking for similar signals at different frequencies then popped up many more examples of what Lintott calls “annoying chirps, caused by human-made sources emitting at many frequencies at once, interfering with the quest for aliens.”
Too bad. It was exciting for a while, but frankly, everyone I know who is mixed up with SETI studies more or less assumed that while an explanation had to be found, it would be one that involved RFI, and so it was. But notice what happened around this event. The news of the data-delving re Proxima Centauri got out to the Guardian, whose reporting on it eschewed sensationalism but nonetheless made a point: Almost anything that happens within a project exploring subjects as sensitive as SETI will come to someone’s attention outside the community sooner than you think.
That makes any idea that a future ‘first contact’ will be covered up by scientists or governments rather ludicrous. Lintott comments:
The idea of a clandestine network squirreling away evidence of signals in the sky is hard to reconcile with the fact that the most interesting signal found by SETI in decades ended up in the press almost immediately. There are something like fifteen thousand professional astronomers in the world, including PhD students, making up essentially a small village, and news travels fast, especially when telescopes are pressed into service globally to follow some new occurrence in the sky.
As Lintott notes, the same thing happened in 2017, when a gravitational wave event was matched with a visual signal detected by spaceborne instruments. This was the first time that newly detected gravitational waves could be correlated with a visual event, which swung telescopes worldwide in its direction. You can’t put a worldwide effort to study a single object into effect without thousands of people becoming aware of it, if only because these observations need to be coordinated.
Image: This picture combines a view of the southern skies over the ESO 3.6-metre telescope at the La Silla Observatory in Chile with images of the stars Proxima Centauri (lower-right) and the double star Alpha Centauri AB (lower-left) from the NASA/ESA Hubble Space Telescope. Proxima Centauri is the closest star to the Solar System and is orbited by the planet Proxima b, which was discovered using the HARPS instrument on the ESO 3.6-metre telescope. Credit: Y. Beletsky (LCO)/ESO/ESA/NASA/M. Zamani.
There is much in Accidental Astronomy that will bring anyone with a casual interest in the field up to date quickly. Current controversies and surprises include interstellar visitors like ‘Oumuamua and 2I/Borisov, the former of which produced a slight acceleration that inevitably raised questions (Lintott is circumspect in his treatment and clearly supports a natural explanation, though an open-minded one). Dyson spheres come up in the discussion of Boyajian’s Star, with its odd changes in brightness that are now thought to be unusual bands of dust that themselves are unexplained. The panoply of observing techniques and deep sky searches come into play in lucid and friendly prose. Befitting his BBC work, Lintott is a fine communicator.
The overall theme is a healthy one. Keep your eyes open, your lens covers off, your mind open. The inevitable corollary is: Don’t get locked into your own thinking to the point that you spend your career defending a hypothesis just because it’s yours. I always think of Voyager approaching Io and sending back images of volcanoes that only one team – Stan Peale, Patrick Cassen, and R. T. Reynolds – had thought would be there. Their paper in Nature appeared with Voyager 1 just three days out from the Jovian system. Talk about timing! Here’s Lintott on the matter:
We astronomers like being surprised, to wallow for the moment in the sense that there is more to understand. It’s a different feeling, utterly, from the way science and scientific progress are often portrayed on screen or in print, where you’re likely to hear stories about singularly clever people who have been blessed, with some clap of thunder, with a dose of cosmic truth before spending their careers trying to prove themselves right. The astronomy I know and love is more likely to involve a bunch of people staring at a screen and looking confused than to feature someone running down a corridor shouting “Eureka.”
So here’s to looking confused. Chris Lintott should be able to keep expanding on this theme in future editions because as the James Webb Space Telescope reminds us, every time we significantly upgrade our hardware, we see things we hadn’t expected to see. Ahead of us is the Vera Rubin Observatory, not to mention a generation of Extremely Large Telescopes (ELTs) that should be able to delve into exoplanet atmospheres around the closest stars. In a few scant decades we’ve gone from the idea that exoplanets are probably uncommon to the realization that they are ubiquitous. Who knows what the next transient in optical or radio wavelengths may bring?
I’ve seen a couple of different sources talking about exoplanets once being believed to be scarce. I was unaware of this being any common belief and unsure why it would be. Without any real data and our system being the only observable I’m puzzled why this would have been the case.
One problem was that back in the day (I’m going back some decades here), the mechanisms for planet formation were still not well understood. So the question of their abundance couldn’t really be determined. When I was a kid, I can remember being told by a teacher that the formation of the Solar System was probably a huge fluke, caused by a passing star, and that we shouldn’t expect to find many more examples of it.
In the book series Foundations of Science the “The Majesty of the Heavens” (pub 1965), in the chapter Formation of the Solar System, the catastrophe theories of the solar system is included when a passing star is the cause of the formation of the planets. These theories were devised at the beginning of the 20th century after Laplace’s theory was abandoned. The catastrophe was either a passing star or that the sun was a binary, one of which was disrupted by the passing star which pulled the planets into their current orbits.
I delight in these older science books, particularly the Frontiers of Science series of cartoon-style explanations by Butler, Bresciani, and Raymond. Even Hoyle’s mid-century explanations of astronomical observations are fascinating given which ones were largely correct and the ones proved wrong.
Hi Alex
“Frontiers of Science” was produced by the University of Sydney. It’s all available online here:
Frontiers of Science
Was my introduction to many advanced SETI concepts, including Bracewell Probes and the Dyson Swarm.
@Adam,
I have visited that site in the past when I was looking to replace the Frontiers of Science ppbk that I had in the UK but got lost during moves abroad.
The story I always remembered and I wanted to use to track down the book was this Rockets, in particular the rocket exhausting light in the image on the right, 2nd from the bottom.
I don’t have the complete set, but I currently have (in different formats):
Frontiers of Science
More Frontiers of Science
Introduction to Physics
Introduction to Earth Sciences
Introduction to Astronomy
The Family of the Sun
The Energy Explosion
I really liked the style and how the stories were presented. Even though these have dated, they are a lovely snapshot of thinking at the time and I loved the optimism for the future expressed in these stories.
One of the first mechanisms proposed for the formation of the solar system is a condensation of the solar nebula to a disk, and the eventual formation of concentric rings of debris which became planets. The same process repeated for the satellites of the planets. As it turned out, this is pretty much what happened! But when this idea was scrutinized, it turned out that our present solar system had nowhere near the amount of angular momentum required for such a formation. Today we know the excess angular momentum was dispersed by magnetic phenomena.
The solar system, when viewed from the North, is composed of objects rotating counter-clockwise and revolving counter clockwise, both in the individual planets, the sun and in the satellites as well. There are exceptions, of course, but this pattern is almost ubiquitous to all the major bodies. The orbital eccentricities are almost circular, and most bodies revolve and rotate very close to the ecliptic. This all suggests some dynamical process related to stellar formation was responsible for these features, so most stars should have planets–they are a normal by-product of star formation.
However, the inability to explain how the excess angular momentum of the original nebula was dissipated led us astray. When I was an astronomy student in the 1960s this topic was still being debated–along with the existence of Martian canals and seasonal vegetation, and the possibility Venus was a jungle world shrouded by perpetual rain clouds.
Even as a child, I always wondered how the strict geometrical architecture of the solar system could be the result of a chance tidal encounter between two stars passing by each other. But that was the favored theory in all the astronomy books I read.
550 years after Copernicus and we as a collective society still have trouble with the idea that we are not special to the rest of the Cosmos. This is one reason why it took so long for astronomers (among others) to accept that there may be more than one solar system. Hey, they didn’t fully accept there could be more than one galaxy in the Universe until 1920 – mind boggling!
Now we know, thanks to HST, that most stars have worlds circling them. And our current estimate at the number of galaxies in the Cosmos has jumped from 100 billion in 2005 – also due to Hubble – to over 2 trillion! And just imagine if the Multiverse is true.
Even mars was a exoplanet, it’s right next to earth
Perhaps the earliest best seller book on extraterrestrial life and civilizations is Walter Sullivan’s “We Are Not Alone”. Published in 1964 it is the first book to show the habitable zones around different types of stars. One fallacy it made was that planets may only be around slow rotating stars. We have come a long way since then, some 60 years ago. We still have a lot of controversy about just how common life is but ideas are improving and technology is making it easier to see the details of what exists. Hopefully with new large widefield optical telescopes coming online and many smaller and very large field nightly surveys instruments, more data will cure our blindness. Some results may show the Holy Grail, an actual artificial signal from another star or a lurker in our solar system…
Yes, and if I’m remembering right, Sullivan’s book was the first title I ever bought on this subject.
Wasn’t the rotational velocity of the stars a theory of Thomas Gold’s? The idea was that the angular momentum had to be distributed by flinging out material to form planets. The analogy of using arms to slow or speed up the rotation of an ice skater.
Thus fast rotating stars had not gone through that process and therefore had no planets.
Observations always trump theory. The better instruments we have, the more and better observations we make, and theories get discarded if they fail to predict the observations. I am hoping that spectrographic data will help to indicate if exoplanets in the [C]HZ are living or not.
Interesting new evidence that may have a large impact on where life and intelligence may develop.
“Dark Oxygen’ Discovered Coming from Mineral Deposits on Deep Seafloor”
https://www.scientificamerican.com/article/dark-oxygen-discovered-coming-from-mineral-deposits-on-deep-seafloor/
Natural batteries producing oxygen seems so far-fetched that the scientist could not believe his instruments… “He sent the instruments back to the manufacturer to be recalibrated. “This happened four or five times” over the course of five years”!
Something that may be going on in places like Europa and exoplanets around M dwarfs where huge amounts of energy are being delivered from flares and in the case of Jupiter geomagnetic activity caused by solar flares. On earth the current solar maximum is charging rocks on the earths surface and causing problems. Are these battery nodules on the deep ocean floor being charged by solar storms?
“Solar storms can be even worse if you live near certain rocks.
New USGS data show how cities have higher or lower risks of blackouts during a powerful sun storm depending on their regional geology.”
https://www.nationalgeographic.com/science/article/solar-storms-worse-damage-if-you-live-near-certain-rocks-geology
This could make for a whole new science for places we now have very little knowledge of. Europa plumes for example, powered by its giant core battery…
@Michael
I had read the paper on these nodules but I hadn’t be able to get any useful information of the importance of the O2. The SciAm article you referenced indicated that it was significant, but what does that mean in context?
Ocean circulation image.
As you can see from the referenced image, abyssal currents are initially highly oxygenated as they are created from the cooling waters of the N. Atlantic. While abyssal metazoan life is sparse, the rain of detritus feeds the bacteria in the sea floor ooze depleting the O2. It is a long way for this circulation to reach the Pacific where these nodules primarily exist.
This opens up a question as to whether this O2 production has a large effect on the O2 concentration near the ocean floor in the Pacific as the currents flow over the nodule beds.
The paper has an equation for the O2 production which might offer some BOE calculations, if the findings are real and not some artifact of nodule extraction from the depths. Have you found anything about this?
If oxygen depletion does occur with the circulation, oceanographic surveys must have done readings that might show this. If O2 is mostly constant, then this might reduce any ecological effect of any nodule O2 production. Have you discovered anything along this line of thought?
Well right of the bat, you are talking about a planet only 300 million years old that covers more or less 3/4th of this planet. Yes, we are lost on our ancient earths crust but do not see the rest of the planet…. See map and you may notice where the oldest part of the ocean floor is:
https://useruploads.socratic.org/epGYlAtQ3qhnPC9zyM2k_age_oceanic_lith.jpg
The history of the ocean floor has gone to the depths of hell in subduction. We are only seeing a very small percentage on land on what the earth was doing billions of years ago. Our knowledge is very little if not at all when we look at the deep abyss. Could the levels in the early oceans O2 created the conditions for life to form. Early earth was a very active planet with major impacts, erosion levels would be high, that is how the nodules form along with hydrothermal vents. Something that our crust bound life forgets is the giant impactors would create huge circler areas of geothermal activity in the ocean crust and supply the metals that would form these nodules. Basically none of this exist now in our present day thinking.
https://www.geomar.de/en/discover/marine-resources/manganese-nodules
The sun was also very active back then contrary to some reports, but as we see in most young stars large and very active flaring. The oceans would give a protective layer against the high energy and geomagnetic activity helping life to develop. Charging from above through the earths Dragon Currents from the sun would energize the deep oceans and create needed elements such as O2.
I still believe that slow gyrating magnetic fields in and around the earth may have initiated the fine weave for RNA and DNA to develop…
https://science.nasa.gov/heliophysics/focus-areas/recent-research/catastrophes-for-life-from-sun/
Hi Paul
Another very interesting post, I can remember reading up on this one at the time, gosh pre covid too, It seems like a lifetime ago now. There was some very interesting speculation at the time and you have alluded to one of these in your post.
I think the next biggest mystery to solve is Browns “Planet 9” out there or not something the Vera Rubin should answer and who know what else it might find.
Cheers Edwin
A very good summary on several levels.
None the least the sentence “……you have to look to find something, and in astronomy keeping the lenses pointed without preconceptions often churns up something rare and strange.”
Which is the basis for my own support that we should keep looking for any kind of civ out there, even though I fully know we are extremely unlikely to find anything in the rather short detection range of a mere 100 to 1000’s of lightyears we got – and depending if any such civ is extremely noisy or not.
And while the grapevine about something new and interesting travel fast, there’s one additional reason that an actual detection never would be hidden.
Everyone in working in science want their name associated with such a major finding, that an non-peer reviewed paper would pop up almost immediately on arXiv.org.
Technology, such as megastructures would likely be more durable perhaps by billions of years over other indicators of contemporaneous civilization, with the downside of increasing likelihood that the civilization may be gone.
A search for such artifacts may also be rewarding.
What is a pity is that the events astro that are a little out of the ordinary are today immediately distorted by the media to make sensational in the eyes of the general public. Very often this “buzz” is unfortunately quickly forgotten by the majority of the population, disappointed – or relieved – not to see E.T out of its saucer. All this does not encourage scientific thinking, especially since we are soaked in a “Hollywood culture” that distorts reasoning.
Very few people in France have tried to understand the trajectory of Oumuamua or its composition when they understood that it was not a spaceship. As for those who still know the WOW signal (so few !) no one questioned the complexity of a possible radio transmission by an ETI or tried to read what J Erhman wrote here http://www.bigear.org/wow20th.htm
In a way it’s a loss of creative possibilities if you consider the millions of human brains. You can do astronomy with very little. Pablo Picasso said, “I don’t look; I find.”
I think the issue is more nuanced. Any fictional representation will distort reality. Plots in novels distort reality in any number of ways, whether science fiction, fantasy, historical, bodice-rippers, or mainstream. Seeing is even more persuasive, but it isn’t just “Hollywood”. I have a number of French films that stretch reality and require leaving your rational brain before watching. Suspending disbelief is inherent in all stories. This suspension of disbelief is age-old, from stories around the camp fire, to the stories and histories handed down even before the written word froze them.
Sensationalism has also long been with humanity. It is used to help rise above the noise of competing stories or interests. Now we have clickbait headlines and breathy stories that tend not to show the circumspection needed by unbiased reality, especially of tentative findings of science.
The other issue is that the scientific knowledge of the world accumulates exponentially. The possibility of knowing about everything has long gone, and we are, at best, reasonably expert in very limited domains, with partial, distorted knowledge of many more. Access to knowledge is far easier today than ever before, but it still takes more time to look up facts than it takes to blather half-truths or total nonsense. And you need time to do this in a culture that is generating ever more distractions at a faster pace. I used to have a book by Saul Wurman called “Information Overload” with instructions on how to manage this firehose of information.
But reality is that most of us have no real grasp of things beyond the human scale in size and distance, and concepts need to be simple enough to understand and retain. Representations of astronomical distances are either done with human-scale analogies or using log10 scales that visually distort what we see represented. No wonder we may think that Mars is close by, and the nearest stars just hop, skip, and jump further.
Herb Simon once said that we use “satisfice” strategies to reduce the costs of search. With the deluge of information, those strategies increasingly look like Daniel Kahneman’s “fast thinking”. We grasp the first things we think we know because we may not have time to do more. And then the proverbial average person on the Clapham Omnibus is not curious and wouldn’t look up anything even if they had a neural link to a global knowledge base. Wasn’t simplicity , but filled with inaccuracies, the joke about the Hitchhikers’ Guide to the Galaxy? Ford Prefect was just updating the slim volume’s entry for Earth people from “harmless” to “mostly harmless”. ;-)
In relation to the radio signal that some thought was from Alpha Centauri but wasn’t, I would like to know what became of another SETI event that took place in 2016:
https://www.centauri-dreams.org/2016/08/27/an-interesting-seti-candidate-in-hercules/
A big deal was made by the Russians that they had detected a transmission from HD164595, a star similar to Sol just 95 light years away in the constellation of Hercules. They were even getting ready to release a paper at an upcoming science conference.
Then, suddenly, the paper was withdrawn and the Russians declared it was actually a signal from an old spysat of theirs. The mainstream media took their explanation without further question (I saw none of them even attempting to inquire what kind of satellite may have tripped them up) and everyone else seemed to drop the subject.
So I ask, eight years later, has anyone bothered to do a followup on this event? If it was a terrestrial satellite and not an ETI signal, which one was the culprit? If not, has anyone continued to examine HD164595?
The big deal SETI researchers always make is that a real ETI signal needs to be detected more than once to confirm its identity. So, which SETI groups are doing followups? Or SETI still in the token efforts phase after all this time?