Astrum Space - We Keep Receiving Mysterious Signals From Deep Space

Episode Date: January 17, 2026

A compilation of ‪ videos exploring the mysterious signals we’ve received from deep space. From the “Wow!” signal, to mysterious radio pulses, we investigate where these signals really came from and what they mean. Could they be signs of alien life?▀▀▀▀▀▀Astrum's newsletter has launched! Want to know what's happening in space? Sign up here: ⁠https://astrumspace.kit.com⁠A huge thanks to our Patreons who help make these videos possible. Sign-up here: ⁠https://bit.ly/4aiJZNF

Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank. WTF. That's what radio astronomer Anna Kapinska labeled the image of an enormous, mysterious blob she first spotted in 2019. Billions of years from Earth, in the realms of... deep space, it appeared like a ghostly ring of smoke, a glowing oddity of radio waves that didn't appear to match up with any known supernova remnant or galactic interaction.

What in the world, in the universe, could this be? It may have been unusual, but this object was not alone. Named odd radio circles, or orcs, the objects we have found seem to encompass everything we struggle to explain in the cosmos. Five orcs have been confirmed since Kapinska's first finding, and several more blobs may fit the profile. What cosmic force is so powerful that it could sculpt a ring of energy a million light years wide, so vast it dwarfs our Milky Way by a factor of ten. Are these radio rings the relics of galactic rebirth, or the dying echoes of some

something we have yet to comprehend. And why haven't we found more of them? I'm Alex McColgan and you're watching Astrum. Join me today as we attempt to unravel one of modern astronomy's greatest mysteries and reveal the four leading hypotheses that could unlock the origin of these objects so odd they defy even the universe's standards. This mystery first began as a result of modern technology. Around the turn of the new millennium, technological advancements in radio astronomy drastically

increased the number of known radio sources from just a few hundred thousand to a couple million. For decades, nobody was able to significantly increase that number, that is, until recently. Radio astronomy was due for another upgrade, and Australia's National Science Agency, the Commonwealth Scientific and Industrial Research Organization oversaw the launch of the revolutionary Australian Square Kilometer Array Pathfinder Telescope, or ASCAP, one of several new radio telescopes coming online at the time. With 36 radio dishes that are each 12 metres across,

what makes the Western Australia Radio Telescope special is its phased array feed, which allows it to image huge areas of the sky at once, unlike the previous generation of radio telescopes. Ascaps' field of view is an impressive 30 square degrees, the equivalent to the surface area of about 150 moons as seen from Earth. The phased array feed allows astronomers to ignore radio signals from things like satellites, which can otherwise create blind spots for radio telescope receivers.

With this new generation of telescopes, radio astronomers are able to detect even faint, diffuse objects. Western Sydney University professor Ray Norris of Zero, later leading the original org discovery, predicted that the Australian Telescope's evolutionary map of the universe project, or EMU, would be part of an extraordinary increase in our knowledge of radio sources across the universe. The project is named after the emu in the sky, a constellation of dark nebulae rather than stars, in the Milky Way galaxy, which has been recognised in Aboriginal astronomy for generations. All of the radio sources discovered up to that point by every radio telescope in the entire history of radio astronomy amounted to about 2.5 million sources, and the Emu project alone

was expected to increase that total to 70 million radio sources. Keep in mind, that only represents the discoveries that were expected to come from just one of the new radio astronomy telescopes. Norris was certain that all of this new data would deliver some major surprises. And it did, much sooner than anyone expected. The EMU project looked at large areas of the sky that other telescopes had not imaged yet, and collected vast catalogues of data, so much that scientists expected they would need the help of machine learning to sift through it all. But it was in the process of

browsing through some of the project's preliminary images that Kapinska, the radio astronomer who discovered Orks, would first notice the oddly shaped radio emissions, using her old-fashioned human eyes. To me, that makes this discovery all the more special. Even with vast amounts of data and machine learning tools, this is an example of how human curiosity will always be an integral part of the scientific process. While browsing these early Emu images, Kapinska started to notice some strange shapes that she couldn't identify as any known space object. On an image of one of these odd shapes, a circle of radio missions like a giant smoke ring floating in distant space, she wrote the label WTF, encapsulating just how baffling

this was. Kapinska had never seen anything like it. After sharing her strange discovery with colleagues, a team of radio astronomers, including Norris and Emile Lank, began sifting through the images searching for more of these circular radio blobs. Leng found a second blob just a few days after the initial discovery, and the team eventually coined the name Odd Radio Circles. At first, they weren't even sure if these were real objects or just some kind of artifact error from the telescope, but they were able to use other telescopes to locate the orcs,

confirming that these odd radio circles were in fact real. The question that followed was, of course, what are these things? Luckily, we've been able to learn a bit more about orcs since Kapinska first noticed one. This is an image of Ork 1 from the Emu pilot survey, a blurry grey scale blob. But luckily, the Emu team also produced this second, colourised and enhanced image that helps to bring out the less obvious features while still maintaining the original resolution. In the color image,

Ork 1 now appears as a hazy green blue blob. Because this hazy blob is only actually visible in radio wavelengths, the color in this image had to be added in so that we can visualize it. It also helps us see more distinct features within the Ork structure. At least a billion light-eat-eastern, years away in deep space. Initial estimate suggested that orc 1 may have a diameter of around 1 million light years.

But more recently, observations have indicated that it may actually be as wide as 2 million light years across. That's 20 times the width of our own galaxy. So we know how big orcs can be, and how distant they are, but what are they? At first some thought these strange rings. might be the remnants of a powerful supernova, but the conditions were all wrong. For one thing, we typically find supernova remnants near the galactic plane, and all of the orcs we've identified are too far away from it.

Not only that, but it appears that some of these orcs might have galaxies in their centers, which is not something we see with supernova remnants. What's more, the scale is all wrong too. supernova remnants are a few dozen light years across, but these orc rings are far, far larger. Big enough to encompass entire galaxies at their center, the orcs we've observed so far are hundreds of thousands, up to two million light years across. These are not supernova remnants. Orcs must be something else. Orcs could also be something we are already familiar with, like the jets from a radio galaxy.

But the vast distance, or maybe an odd angle, might obscure our ability to identify them. Since the initial discovery of Ork 1, astronomers have had the chance to observe it with additional telescopes, revealing an object that appears to be at the center of the circle that can be seen in both visible and infrared light. Using the South African Mieckat Radio Telescope, An array of 64 interlinked receptors, Norris and his team observed Ork 1 for 10 hours to create an image of the circle.

They overlaid that on optical data from the Dark Energy Survey to reveal an elliptical galaxy in the center of the Ork. With this, they were able to estimate the central galaxy's distance from Earth at around 5 billion light years away. Not only did they find this central elliptical galaxy, but the high. High sensitivity image also revealed a complex in a structure of knots and arcs, with additional galaxies found at these knots. If Norris and his team were correct, and this elliptical galaxy is indeed located near the centre of Ork 1, then it might have had a hand in creating this radio circle. However, it's also possible that the galaxy's location is a coincidence, as it may just be

near the apparent center of the ork, rather than the actual center. Armed with this new image and information, in their 2022 paper, Norris and his team considered three different origin stories for the org, with the data not favoring one hypothesis over another. The first possibility was that Ork 1's spherical shell was the result of a cataclysmic event in the elliptical host galaxy, like the merging of two supermassive black holes, for example. In this scenario, a merger of two supermassive black holes would send a shockwave out in all directions, accelerating electrons in the intergalactic medium. This could result in a bubble of radio emissions, which could appear to us as a circle of

radio emissions with a brightened edge or ring. If this were the case, we would expect the orc to contain a supermassive black hole or an active galactic nucleus. And not only does orc 1 show evidence of a radio-loud galactic nucleus like we would expect if this hypothesis were correct, but so do two other observed orcs lending further credibility to this hypothesis. The second possibility offered by Norris and his team for Ork One's origin was that it could simply be radio jets from a Radio Loud active galactic nucleus, or AGM, viewed and on. Radio Loud AGMs are a type of galaxy that emit large amounts of energy from its nucleus in the form of two plasma jets, as matter falls into a supermassive black hole at their center.

And as I mentioned, we already know that ANGs are present in many of the orcs we have observed thus far. If we were to view this kind of system end on where the two jets were superimposed, it could create the appearance of what we see with Ork 1, lobes of radio emissions superimposed with a host galaxy at the center. However, we still need 3D simulations to help us work out whether or not. not these particular ANGs are producing radio jets, and if so, whether or not we are viewing them head on. The third and final hypothesis for an origin story could be that the radio circle of Ork 1 is caused by what's called a starburst termination shock.

In this explanation, millions of stars would have been born during a brief, intense period of star formation in the elliptical host galaxy. During this time, new stars would have been born at a rate much higher than normal, and would have lasted for just a few tens of millions of years, just a blink on the cosmic time scale. These stars would emit solar wind that expands out into space over billions of years, exciting electrons, and creating a spherical radio emission bubble like what we see in Ork 1.

While the team modeled this possibility in more detail than the first two hypotheses for the formation of Ork 1, showing mathematically how this scenario was plausible, Norris was clear that the data did not favour this explanation over the others. So while we do have several promising ideas, the origin of Ork 1 is still as mysterious as the odd radio circle itself. As each new orc has been discovered, the only thing we seem to know for sure is that not all orcs are created equally. After all, the name odd radio circles is meant as a descriptive name, like an umbrella term

for any odd radio circle that can't be described by any existing type of object. So while all orcs may include odd radio circles, each individual orc may have its own unique origin story. The discovery of Ork 2 and 3, the second and third odd radio circles to be identified, didn't do much to help solve the mystery of how orcs are created. In fact, they introduced even more questions. Seen in this grayscale image, the two orcs appear to be very close to each other, nearly touching. They are roughly the same size, but on the right side of the image, Ork 2 is bright and clearly ring-shaped, while Ork 3, located to the left, is faint and appears more like a disc.

In fact, Ork 3 may not even be recognizable in the greyscale Emu image if it weren't for the light grey speckles seeming to cluster together into a circular shape right next to the more distinct ring shape of Ork 2. Now take a look at this colour image of Ork 2 and Ork 3. The diffuse radio emission has been enhanced in red and overlaid on top of the original radio pattern in green. You can see the obscured green colour behind the red glow, where the ring shape of Ork 2 is located, and to the left you can see its fainter sister circle of Ork 3, only visible in diffuse red. The proximity of these orcs would suggest that they are related somehow,

but if that's the case, why do this? they appear so different. As much as I'd like to tell you that we've solved this curious case of Ork 2 and Ork 3 since their discovery, which was published in 2021, the nature of these sister orcs remains an unsolved mystery to this day. Before moving on to the theories for Ork 4's origin, I've got to mention Ork 5, which was discovered in Australian Square Kilometer Array Pathfinder Data in 2021. While we don't have any leading theories for Ork 5 specifically, this orc was found to have

a central elliptical galaxy, like Orcs 1 and 4, and interestingly, Ork 5 was the only one found to have both this central galaxy and a nearby neighboring galaxy found at approximately the same distance from the Ork ring, which suggests these two galaxies are likely interacting gravitationally. While there may be some repeating characteristics, for every orc we've confirmed so far, it seems that each one has their own unique qualities. Of course, as we discover and confirm more orcs, it may be that this won't be the case in the future. But with so few orcs and so little observational evidence,

it's been difficult for scientists to nail down one theory for their origin. And that brings us to Ork 4. dubbed the Cloverleaf Org because of its irregular shape. Of course, this turned out to be another unique case. First identified in archival data from the giant meterwave radio telescope, the Clover Leaf Org would end up being the most extensively observed and imaged odd radio circle to date, having been observed in radio, x-ray and visible wavelengths.

In this stunning image of the Cloverleaf Ork, wavelengths from several observations have been combined with radio emissions shown in red, optical wavelengths depicted in white to yellow, and x-ray emissions in blue. This orc resides some 600 million light years from Earth and stretches more than 325,000 light years across, a little more than three times the width of our galaxy. In 2024, astronomers at the WM Keck Observatory in Hawaii detected strong fluorescent light from oxygen atoms coming from the cloverleaf orc, stretching across 130,000 light years of the orc's massive structure. This oxygen two nebula of heated, compressed gas, also called shocked gas, seemed to have

been created by a fast-moving explosion, according to. Alison Koehl, astronomer and astrophysicist at the University of California, San Diego, who led the research team and conducted this study of Ork 4. Since the Cloverleaf Ork also has a central elliptical galaxy, Coyle stated that one possible explanation was that this orc could have been formed by a starburst termination shock event, one of the three possible hypotheses for the origin of Ork 1. The team was able to calculate the age of the stars inside the galaxy,

galaxy in the Cloverleaf Orp and found that they are 6 billion years old. Using this and other data, they ran a simulation that showed how a similar structure to the Cloverleaf Ork could have been created by a starburst event that caused a high mass outflow rate. Both the radio emission sphere and this gas nebula sphere could have been blown out by the central galaxy by the shockwave of combined supernova explosion. While this is an exciting possibility, especially because of its similarities with one of the Ork 1 hypotheses, it's not the only possibility.

That same year, using the European Space Agency's XMM-Newton X-ray telescope, a team led by scientists at the Max Planck Institute for Extraterrestrial Physics in Germany, detected diffuse x-ray emissions for the first time in an odd radio circle, coming from the Cloverleaf Ork. Based on their observations, the same team that observed the X-ray emission, led by German astrophysicists, Bulbul and Chang, hypothesized that the Cloverleaf Ork may be linked to a cosmic dance between two groups of galaxies. The X-ray observations suggest that the Cloverleaf Ork could be the result of a messy merger of two galaxy groups that gravitated towards each other. This type of a galaxy merger could have created shockwaves that would leave behind, a gigantic bubble of radio emissions, like what we've seen in observations of this org.

However, a lot is still unknown, and it's unclear why this set of galactic groups would produce such an org, while other similar galactic group mergers don't seem to leave behind the same gigantic bubble of radio emissions. As you can see, the mystery of how orcs came to be is far from solved. In fact, it's still up for debate whether the cloverleaf orc is in fact an orc at all, seeing as it is more of a diffuse cloud and lacks the telltale bright edges of radio emissions. Norris points out that similar cloverleaf shaped radio clouds have been observed in other galaxy groups, not all of which are associated with orcs.

The key to resolving which objects are part of the orc family and which are not is more data. Deeper radio and x-ray observations may be able to help identify more complex structures and help differentiate between actual and near-a-orcs. Luckily, several other candidate orcs have been identified, and they may offer additional data for astronomers to study and compare to the already known cases. Now, instead of WTF, the side note on these strange radio missions has a proper name, Orcs. But even though the jury is still out on how orcs came to be, we are constantly gaining new insights from the likes of Project Emu and ASCAP. While studying Emu data from a nearby dwarf

galaxy called the small Magellanic cloud, astronomers spotted the ghostly remains of two supernova remnants that were previously unknown to science, adding to our catalogue of celestial objects. In addition to those, Another nearby supernova remnant was found by using the Emu survey in 2023, and turned out to be one of the closest supernova remnants to our Earth at just 4,200 light years away. This supernova remnant, known as this, was found to be about 130 light years across, and is thought to be just 13,000 years old. Not only has Emu aided in the discovery of previously unknown supernova remains, it is It is also paving the way for using machine learning and the power of citizen science to

identify and catalog some 4 million radio sources, which could include orcs, as part of a project called the Radio Galaxy Zoo, Emu, or RGZ Emu. As of 2025, the project has had more than 2,000 volunteers and has helped to classify more than 92,000 sources. But the coolest part, you can join you. in and be part of the citizen science project yourself. To learn more, visit zooniverse.org and search for the Radio Galaxy Zoo Emu Project. As our tools continue to improve, I believe that astronomers are bound to discover more orcs and even more objects we don't know even exist yet.

We may learn not just how these radio rings formed, but we could also learn more about the life cycles of galaxies, the effects of starburst events, and how we may be able to trace gas from ancient events far outside their galaxy of origin. For now though, the mystery of the origin of these odd radio circles persists, although with several promising hypotheses. And to unravel this mystery, astronomers will have to conduct cosmic archaeology on a scale almost too big to fathom. In 2022, astronomers using the Murchison Wide Field Array discovered a strange new radio signal that was arriving every 22 minutes. The astronomers were no strangers

to such repeating signals. They typically come from pulsars, neutron stars which send intense pulses of light across the universe as they rotate on their axis. But as they began to look deeper into records of past observations, they realized this signal had been arriving at Earth since at least 1988, with remarkable stability, far more stable than is expected for a pulsar rotating every 22 minutes. If it was a neutron star, it was unlike any they had seen before. So, where was this signal coming from? I'm Alex McColgan, and you're watching Astrum. Join me today as we grapple with the mystery that lies behind this signal, which will challenge our understanding of some of the most

or inspiring objects in our cosmos. The location of the source named GPMJ1839-10 is roughly 18,000 light years away. Its signal arrives as pulses that can last any amount of time between 30 seconds and 5 minutes. These pulses can appear at any time in a window of just over 6.5 minutes, which is centered on 22 minutes after the previous pulse. To us, this may seem like a great deal of variation. 30 seconds and 5 minutes are very different durations, and the pulse arrival varying by over six minutes doesn't paint a picture of a very stable source.

But neutron star dynamics can be very complicated, and if the source is indeed a neutron star, then many factors can affect the duration and arrival times of the pulses that we receive. Nevertheless, the astronomers were able to spot this signal hiding in data. from the last 35 years and used this expanded data set to average out the fluctuations. They calculated that the source was rotating once every 21 minutes and 58 seconds, as well as how much it had slowed down. But to their surprise, they calculated that this rotation period remained unchanged over

the past 35 years, even though it is expected that the source will slow down as it radiates energy into space. We can only say for sure that if the source has slowed down, its rotation period would not have increased by more than 0.28 milliseconds over the 35-year period, because otherwise, we would have been able to detect this in our data. This is an absolutely minuscule amount, and it shows that whatever the object is, is spinning with remarkable stability. This usually isn't odd for a lot.

a pulsar. These are the timekeepers of the universe, the clocks of the cosmos, mechanistically ticking away with such certainty that we can use them to measure time across vast stretches of the universe. However, this level of stability is odd for a pulsar that is rotating so slowly. To understand what makes it odd, we need to recap how pulsars work and what makes them slow down over time. Pulsars are neutron stars. the leftover cores of dead super giant stars, which, barring black holes, are the densest objects in the universe. Planets like our own are made up of atoms, which consist of over 99.999% empty space, due to the vast separation between the electrons and the incredibly dense nucleus they are whizzing around.

But imagine an entire star made purely out of the neutrons that are found in the nucleus. No electrons, no protons, no empty space. Merely a teaspoon of it would have as much mass as 11 times that of the entire human population, all 8 billion people. A typical neutron star is around 35% more massive than our sun, and squeezed into a sphere that has the diameter about as long as the island of Manhattan. To call it dense would be an understanding. For reasons still unknown to astrophysicists, the extreme environment gives rise to an incredibly strong magnetic field.

What does this have to do with the signals we receive from pulsars? Where do the light waves come from? To answer this question, we need to understand a complicated process that gives rise to the signal, an exponentially growing shower of light and matter, all spawning from a single electron. Near the magnetic poles of a neutron star, an electron can be accelerated by the magnetic field and emit a so-called curvature photon, tangential to the magnetic field line. This marks, if you like, the start of a pulse. The curvature photon moves in a straight line until the angle between its momentum and

the magnetic field line becomes too great. Once this angle reaches a threshold, the light dissipates and imbues its energy. energy into the quantum field of electrons. An electron is created alongside its antiparticle, the positron. The electron positron pair has some momentum perpendicular to the magnetic field lines, which they spontaneously dispose of in the form of synchrotron photons. These two synchrotron photons can each then produce another electron-positron pair after they reach the threshold angle between their momentum.

and the magnetic field lines. This process repeats again and again, exponentially increasing the amount of photons and electron-positron pairs created until the synchrotron photons no longer have enough energy to create electron-positron pairs, putting an end to the cascade. These photons then beam out into space, while the original electron continues its journey, generating more curvature photons and more cascades as it moves along the magnetons. magnetic field lines. This pair production cascade is why the light of a pulsar is so intense that we can detect

a signal from this tiny stellar remnant thousands of light years away. But why do we see this light as pulses rather than a continuously glowing beacon of light shining at us? This is because the magnetic poles of a neutron star are rarely ever aligned with its axis of rotation. Like on Earth, the magnetic North Pole that our compasses point to isn't the actual geographic north pole that Earth rotates around. So the pulsars are like great lighthouses, sweeping their beams of light around the cosmos

as they spin. And for an observer far away, like us on planet Earth, we see the beams sweep past us again and again as the pulsar completes its rotation on its axis. other pulses of light that our telescopes can detect. However, this is light with very long wavelengths in the radio part of the spectrum, meaning only a radio telescope can detect it. The light that the cascade produced is of the same wavelength, with the peaks and troughs of the light waves fluctuating in unison. The light waves are also polarized, which means they are all aligned along the same axis. This is a hallmark of neutron stars, and this is

precisely what we observe in the 22-minute signal. The signal also has fluctuations that last between 0.2 to 4 seconds, where the axis of the light's polarization suddenly changes by 90 degrees, perpendicular to the original axis, and then back again. This effect is yet another signature of the cascades of the poles of the pulsars. So much of our data points to a pulsar being the signal that you'd think this was an open-and-shut case. But one variable that we've mentioned earlier throws this entire theory into doubt, the slow rotation rate of the neutron star, or rather the combination of the slow rotation rate

and the high stability of the rotation rate of the source. You see, as pulsars lose energy by shining their powerful beams into the cosmos, conservation of energy will ensure that the pulsar slows down. Eventually, the pulsar will slow down so much that it can no longer power the pair production cascades, and the light emission starts to shut off. The pulsar has entered the so-called Death Valley. This graph plots neutron stars based on their rotation period on the X axis, and the rate of change of their rotation period on the Y axis. Death Valley is shown in this grey band running through the middle, and any A pulsar that has properties below this line should not be shining as the bright lighthouses

they usually are. We see that our signal is below even the lowest line marking the Death Valley, meaning that if it were a pulsar, it should be well and truly switched off, and yet we are detecting it. Look at the cluster of other known neutron stars on this graph. They usually spin between 10 times a second to once every second. In comparison, our signal has a spin rate of once every 1,318 seconds, over a thousand times slower than the typical pulsar.

This would be fine if it was also slowing down quickly, which equates to moving this data point upwards on this graph above the Death Valley. Such rapid energy loss would power the pair production cascade necessary to light the beacon of the neutron star. the neutron star is mind-bogglingly stable, and it makes no sense that we can detect it. The astronomers who found the signal considered an alternative mechanism that might explain how a neutron star with such properties might have produced this light. Maybe the neutron star is a magnetar, a neutron star that has an unusually strong magnetic field,

greater than 10,000 times the strength of the weakest neutron star magnetic fields. Magnetars are known to undergo starquakes, cataclysmic events that release the tension in the upper crust of a neutron star. These stresses are produced by the strong magnetic fields of the magnetar, as well as the slowing down of the magnetar rotation. A fast spinning magnetar will bulge in the middle due to the central fugal force distorting the star from a perfect sphere. As the magnetar slows down, the outer layers need to readjust to adjust to the middle.

a new equilibrium and lose some of the bulge they have. The crust snaps into a new position, causing magnetic fields to temporarily realign and powering the release of the energy as light that we can detect on Earth. The most powerful starquake detected, that of SGR-1806-20 in 2004, released so much energy that if it had taken place as far away as 10 light years from Earth, Earth, it would have caused a mass extinction event. If something is able to light the beacon of a dead pulsar, it would be this. So could GPMJ1839-10 be a magnetar that has undergone a starquake?

Have we resolved the mystery of the 22-minute signal? It seems not. We expect these starquakes to also emit light in the X-ray part of the spectrum, yet no X-rays can be detected from the position of the source roughly 18,000 light years away. It also wouldn't make sense for a magnetar outburst to be going on for three decades. The starquake is a temporary phenomenon, and the energy dissipates within a few years at most. It is simply incomprehensible that this signal would have existed for 35 years if it was indeed a magnetar.

Once again, the unique properties of our signal exclude it from being a neutron's signal. star, even an unusually powerful one that has undergone a special event such as a star quake. But what else could the source of this mysterious signal possibly be? The astronomers who discovered the signal proposed a few alternatives for the identity of the source. One possibility is a highly magnetic white dwarf. A white dwarf is another type of remnant left from the recent death of a star, but one that didn't have enough mass to collapse the empty space in the atoms to become a neutron star. A remnant that has an unusually strong magnetic field could produce radio emissions, and as

it is not a neutron star, it could get away with being as slow and stably rotating as the source of our object while doing so. The issue is, this would require an exceptionally strong magnetic field, greater than any we have spotted on a white dwarf. A.R. Sko is the only known radio pulsar that is actually a white dwarf, and its radio missions are a thousand times less luminous than the source of our 22-minute signal. So if a white dwarf is unlikely, what are our other options? Astronomers have observed low-frequency radio waves coming from the interactions between stars

and exoplanets, as well as a binary of two brown dwarfs rotating around each other, But this emission is typically weaker, around 100 million times weaker than the source of our signal. In the end, it seems like none of our theories can explain the 22-minute signal. While the unresolved question about the source of the signal may feel frustrating, this is precisely the kind of mystery that astrophysicists look for. When scientists find new data that challenges our long-held theories, They can usher in revolutions in our understanding of the universe around us. Here, our already shaky understanding of neutron stars is being challenged.

The astronomers are confident that the ease with which they identified this signal means similar sources lie out there in the galactic plane, waiting to be identified. Just like GPMJ1839-10, the other signals might already be lurking in the data we have collected. identifying more of these signals will shed light on the process powering emission beyond the neutron star Death Valley. Whatever lies behind the 22-minute signal, we are sure to learn of an entirely new phenomenon that we have never seen before. Isn't that exciting?

What do you think could be the source of the 22-minute signal? Let me know in the comments below. In the Milky Way alone, there are thought to be 100 billion planets. Of these, 30 million are thought to exist in Goldilocks zones that are just the right distance away from their sons to support life, while also containing the right mix of chemical elements that life like ours can arise from. In all the 13 billion years of the universe's existence, if just a tiny fraction, if just 1% of these went on to become civilizations capable of reaching out into the cosmos, then

we should be seeing signs of thousands, if not millions of alien races running across our galaxy. And so, in the words of Nobel Prize-winning physicist Enrico Fermi, in his famous Fermi paradox, where is everyone? I'm Alex McColligan and you're watching Astrom. Today we will be exploring some of the possible answers to this question, because although we don't know for certain whether aliens exist, there are actually. some surprising barriers that might stop us from seeing them even if they do. Let's start by addressing the elephant in the room. Maybe there's no one to see.

In our last video, we explored the possible odds of alien life existing and found that if it was true that it's quite difficult for life to arise from non-living materials, or if it's unlikely that life would go on to become intelligent as we have done, then it's entirely possible that there would be no ships or signals in the sky simply because there are no aliens. We would be the first ones to ever make it this far. All other planets could be empty and desolate. It would then be our opportunity to spread out across the universe and discover all these empty rocks, and the only life we'd ever encounter is whatever we brought with us from Earth. While this is a perfectly reasonable possibility, there is no conclusive evidence to prove it wrong.

This is not the only explanation that exists for why the sky isn't full of signals. We should also be aware that we are constrained by a surprising natural limitation. For us to discover or make contact with an alien civilization, one of two, Two things needs to happen. Either we need to send out a message to an alien civilization and then have them send a message back to us, or the alien civilization needs to have made the first overture, messaging us directly. There are different ways of doing this. For instance, we might be sending spaceships to each other, or we may be using unmanned

probes, but there are significant issues with doing anything other than sending messages. Sending a spaceship is a tricky business. At the current speeds our spaces are capable of, it will take potentially millions of years for an astronaut to reach their destination. The Voyager 2 probe took about 49 years to even leave our heliosphere. The nearest star is four light years away. In other words, it would take over 81,000 years to get even there, or about 2,700 human generations, and that's assuming that we have aliens as our closest next-door neighbors.

Even if we make allowances for technology to improve, it takes colossal energy to accelerate an object up to light speeds. Actually, it would take more energy than exists in the universe for reasons we won't get into here. Mass just does not like to travel at those speeds. So, unless we or our alien friends are able to come up with some kind of work around, most likely the easiest way to communicate with other civilizations is to send them radio signals. In fairness, it's not implausible that this speed cap will one day be broken. Scientists have hypothesized some promising things involving moving the space around you in warp bubbles rather than by moving yourself directly.

The speed of light limit only applies to movement within a local area. So if it's your local area that's moving, you're fine. We actually have examples of this in nature around black holes, which I explore in one of my other videos. But until that becomes a scientific reality, let's just go with the fact that it's much easier to call than to visit in person. It's significantly easier and cheaper to send out light or light. radio waves, as simple as turning on a sufficiently large light bulb. So let's assume that this is how our first contact with aliens will occur. Even here, however, we hit a roadblock.

Radio signals and light are more than capable of travelling at relativistic speeds. It's called the speed of light for a reason after all. However, that's its limit, light speed. Just less than 300 million meters per second. No signal can go faster than that, and this in turn limits how far we are able to see through space. Any signal from us would need to travel out across space before reaching alien life, and then, even if they decide to respond immediately, their response would need to travel all the way back,

if they decided to respond. Let's imagine that happens though. We only invented the radio in the mid-1890s, so we have not yet. not really been able to do this for very long. As such, we would only be able to exchange a message with aliens who lived at most 60 light years away from us. 60 years for a signal sent out in 1900 to reach the alien civilization and 60 years for it to come back.

Our galaxy is roughly 100,000 light years across, so the 60-year light bubble we have we could have communicated with is truly tiny. In fairness, this limitation goes away if the aliens contact us first. After all, we are now receiving light in the James Webb Telescope that has been traveling for 13 billion years from nearly the beginning of the universe. If an alien civilization came into being around 2 billion years ago, and they've kept existing since then, that means they now have a 2 billion light-year bubble from which we could technically see them. A 10 billion-year-old civilization now has a 10 billion light-year bubble.

But if they were 10 billion light years away and only 9 billion years old, they would be completely invisible to us. Assuming that such far-away aliens exist, why aren't we seeing any of them? Where are their signals? Well, this line of thought may rest on a faulty assumption, that there haven't been any signals coming in from the stars. There have been signals. We're just not sure what they are. Let's explore this with a fascinating example. In 1961, in their pursuit of evidence for the existence of alien life,

which is worth noting because it opens up the possibility of confirmation bias, researchers at the Ohio State University finished work on a specialized telescope called Big E.N. It was the size of three football pitches, and worked on a similar basis to modern-day telescopes, in that it captured signals using its large mirror on one end, and bounced them through smaller mirrors on the other into two receivers in the centre, where the results were then processed. You may notice that these captured dishes are just wireframes, though, not true mirrors. This is because Big Ear was a radio telescope.

wasn't trying to see with visible light. The way Big Ear worked meant that it was more limited in its motion than a telescope that could rotate in any direction. Big Ear could only tilt its primary reflector up and down, which meant that it was somewhat limited to only listening to a point in a narrow strip of space at any one time. This was cheaper and easier to design, and the designers had an idea that would let them get around Big Ear's limitations. They built Big Ear at just the right orientation so that the rotation of the planet would be what turned it left and right. With the Earth turning it one way and with its tiltable reflector adjusting it along the other axis, you could point Big Ear towards any point in the sky if you have enough patience.

Quite a clever solution. Big Ear's direction of attention would sweep around the night sky in large circular arcs, listening out to try to spot any unusual signals that we did not have a natural explanation for. And sure enough, in 1977, Big Ear found something. On the 15th of August, a 72 second long pulse of radio waves came in that were 30 times more powerful than anything Big Ear had heard before in the background chatter of the universe. It was so out of the ordinary that the researcher who found it wrote wow on the computer printout when they saw it, giving it the historical name of the wow signal. It was incredibly uniform.

It rose in intensity, peaked, and then dropped back down in a smooth motion instead of the erratic fluctuations you might have expected from cosmic radiation. This indicated that whatever had made the sound was broadcasting consistently, kind of like the beam of a lighthouse sweeping out across the stars, with us turning to look at it and then turning away again. Except it wasn't consistent. Due to Big Ear's design, researchers had to wait a few minutes before the second ear of Big Ear moved to look at that particular patch of space the wow signal had come from,

And when they got there, the signal had vanished. Ever since then, despite checking back in from time to time, we have never heard another wow signal come from that region of space to this day. So what was it? A fault in the machinery of Big Ear? A passing comet that threw out a momentary burst of signals, or an alien civilization trying to communicate. The fact of the matter is, we don't know.

It's possible that the wow signal has a perfectly natural explanation. After all, when the regular, consistent pulses of x-rays from pulsars were first discovered, some people thought that they were aliens trying to communicate before the real explanation was found. Maybe we will one day find another wow signal, and we'll see that it was nothing alien in origin at all. But there's a technical point that needs to be made here. If I were the scientist in charge, I would point my telescope at the point in the sky that the wow signal came from and would wait to see if anything else came from there. If I didn't, another signal might come in and I'd miss it.

But consider the way Big Ear was constructed, it rotates only within the rotation of the Earth. It physically can't stay looking at the same place for more than a few moments. As such, we have no idea whether more signals came in from that region of space or not. Hundreds could have come in over the next several hours, including an entire orchestra performance. But as Big Ear wasn't listening in that direction for more than a moment in the day, it would have only heard a single note.

This highlights a conscious decision on the part of organizations like SETI, who are seeking intelligent life in the universe. Because resources are limited, and space is vast, they lack the time and funding to take a telescope and point it for potentially decades on end at a single place, just to see if aliens want to talk to us again from that spot. Instead, they favour broad sweeps of space to cover as much ground as possible, hoping to get a lucky hit. If they were fishing, rather than leaving their line in the water at a single point, they're casting and casting. seeing if anything bites immediately, and moving on if nothing does.

This approach is more reasonable than my analogy makes it sound, as aliens are not fished to be attracted to allure, or scared off by a splash of a telescope looking at them. And although the first process is more methodical, there's every chance that if you just sweep your telescope across the sky, you will encounter some evidence or signal. The problem comes with the follow-up. There have actually been numerous signals like,

like the wow signal that radio telescopes have picked up over the years, strange and unusual bursts that we have no current explanation for. But because we aren't focusing on them and thoroughly following up over years of continued dedicated study, we are missing a lot of information, and as a result we end up with weaker conclusions. Which brings us to our conclusion. Perhaps we are seeing no aliens simply because of our method. Of course, these are just a few of many possible theories.

For this video, I've tried to focus on some of the technical limitations to finding signs of alien life. However, there are other, more theory-based explanations that lean more on speculation. They are fascinating though, and give us interesting insights into our own civilization. So if you've enjoyed this subject, then I'll go into them in another video. Do you think there are aliens up in the night sky? If so, why do you think they've not spoken to us? Be sure to leave your ideas in the comments below.

The search for alien life is a difficult one. How would we know that aliens exist? An obvious answer would be if they visited our planet en masse, if, like in the film Independence Day, their sources floated above every city in the world, or perhaps if their envoys met with us, shaking hands with our world leaders, while cameras broadcast at the moment on national television. Or maybe if they started trading with us and their inventions and resources began appearing in our everyday life. There is, fortunately or unfortunately, not much evidence that this has ever happened. But while visits from aliens would certainly be preferable, that's not the

only possible way aliens can prove their existence to us. It's much more plausible that they would do so with their signals. We've spent a lot of time on this channel discussing some of the reasons why aliens might not have talked to us, but on the flip side, what are the strongest pieces of evidence that they have already done so? Which signals are considered the best candidate so far for a message from an alien civilization? I'm Alex McColgan, and you're watching Astrum. And rather than explain why we haven't heard from aliens, today let's look at where perhaps

we already have. Obviously, when it comes to alien signals, there is some ambiguity as to what exactly we are looking for. Aliens are, after all, alien. We are not quite sure what to expect from them, as they will have likely evolved in conditions different to our own, and may well have cultural outlooks that make perfect sense to them, but are completely obscure to us. Their definition of a good way to say hello to the universe might be very different from

hours. Researchers looking into possible signals from other planets have to remain very open-minded about what an extraterrestrial signal might look like. But that means such signals can get confused with signals from natural sources that we simply do not understand yet. How can we tell the difference? Let's look at a few examples to show you what I mean. In 2019, as part of the Breakthrough Listen Initiative, the Parks, Maria, The flying telescope in Australia was observing Proxima Centauri, the star nearest to our own. It was recording data to learn more about stellar flares. But when SETI researchers, a collective term for the search for extraterrestrial life, went over

the data it had collected sometime later, they found something unusual, a signal, which later came to be known as BLC1. Could the star closest to our own actually harbour advanced alien life? The signal was fascinating, as it could not easily be explained away by conventional sources. It lasted for several hours, which is longer than the time it normally takes a human satellite to pass by overhead. It had signal drift, its frequency was shifting, which implied possible movement relative to the telescope, so it likely wasn't coming from a stationary object created.

interference on Earth. One of the most compelling things it had going for it was its thin, narrow-band signal. In nature, radio waves are never so narrow in their range. They always fluctuate. Unless there exists some natural source out there we've not discovered yet, the only thing that produces such a concise signal as this is technology, either human or alien. When no obvious explanations for existence could be found amongst human sources, Naturally, scientists wondered, could this be the signal from alien life they had been looking

for? Along with the wow signal, which we looked at in a previous video, BLC1 is one of the strongest candidates for signals that may have been created by alien civilizations. And yet, even this signal has its drawbacks. Scientists could not link it to any sources of obvious interference from technology on Earth, But on closer examination of the data, it did match other radio wave signatures that came up on other days of the search, except these other signals occurred no matter what direction the telescope was pointing in.

Neither were they able to detect BLC1, the signal from Proxima Centauri, with later observations. So while they don't know exactly what interfered with the telescope to produce BLC1, the odds of it being interference are nonetheless quite high. Let's take a look at another candidate, a somewhat mouthier SHGB02 plus 14A. When one of the first SETI experiments, Project Osmer, was started in 1960 by Frank Drake, it began on the basis that if alien life were to communicate with the rest of the universe, they would do so at frequency 1420 megahertz.

The logic behind this was that this was the frequency emitted commonly by hydrogen, one of the most widespread elements in the universe. Aliens looking to establish communication with other civilizations might use such a frequency as a sort of common ground, a wavelength that probably holds a special significance to any race. This might have been a leap of logic, but it certainly made SHGB02 plus 14A of interest later. Because this signal, let's just call it SHG for the rest of the video, for the lack of a punchier name, did indeed broadcast at this exact wavelength. SHG was spotted on three separate occasions in 2003, using the Aricebo telescope and the

computational power of 5.2 million home computers as part of the SETI at Home Initiative, a rather cool program that is sadly no longer running. SHG had no obvious explanation for his origins in nature, and it didn't appear to be interference. But it was also too weak to say for sure whether it was clearly technological or not. On top of that, its location was peculiar. It came from a spot devoid of stars up to 1,000 light years away from Earth, and although it experienced drift, it did so in a manner that made scientists suspicious. If a signal originates from a planet, then there are a few things we might reasonably infer.

A signal being broadcast from a planet, either on the surface or an orbit just above it, would likely experience some Doppler shift as it alternated from moving away from us to coming towards us through the circular path it was taking in space. There would also be movements where it dropped out of view entirely as it moved behind the planet. While SHG did indeed experience fluctuation in its signal frequency, ranging from 8 to 37 hertz per second, this would only come from a planet that was rotating 40 times faster than Earth, which seemed high. It was also strange that each time the signal was spotted again, no matter where it had

been when it had last been sighted, it always began at 1-420 megahertz. The odds of you looking at an orbiting transmitter on three separate occasions and each time spotting it, starting off at the exact same location, is incredibly slim, which is what you'd need for this to make sense. This observation pointed to it being, more likely, SHG was some kind of glitch in the technology. By looking at the process by which the BLC1 or the SHG signals were evaluated, we gain an interesting insight into how SETI determines whether something might be of alien origin.

To me, it is a method that lines up best with this quote from Sir Arthur Conan Doyle, in the words of his famous detective Sherlock Holmes. When you have eliminated the impossible, whatever remains, however improbable, must be the truth. Each time researchers came across a new signal, they began by eliminating all possible alternatives. Could it be interference from a passing satellite? Is there anything in nature that we know of that could be producing this effect? Can we in any other way explain why this signal is here and behaving the way that it does? So far, alternative explanations have been found for these contenders for alien communication. Even on the occasions where human interference can be ruled out entirely, that still leaves

open the possibility that these mysterious signals might just be undiscovered natural phenomena, And that is precisely the current discussion around the last candidate for alien signals I'd like to leave you with today, fast radio bursts. If an alien civilization were ever to be detected, it might not be intentional on their part. Powerful engines activating or beams firing all might release bursts of energy that give away a galactic civilization, which makes fast radio bursts or FRBs interesting. They are, just as the name suggests, very fast bursts of radio waves. We have detected hundreds of these strange millisecond-long bursts across the sky.

Scientists theorized that there might be thousands of them occurring every single day. They have mostly been detected outside our galaxy, but one was detected within the Milky Way in 2020, so they're not completely foreign to us. They seem to be coming from extremely powerful magnetic fields. And as of yet, scientists have no clear idea about what their origin might be. There are plenty of theories. Perhaps they are emitted by neutron stars, or maybe black holes. But there is no proof that puts any one theory over another, including that of alien technology. The Chime Telescope in Canada has a unique design that makes it ideal for detecting these

fleeting blips in the cosmos, avoiding the pitfall of other telescopes, rather than the Rather than pointing at any one point in the space, Chime's multiple cylindrical parabolic reflectors are able to draw data from an entire swath of the sky at the same time. It began detecting in 2018 and is still going strong to this day. It has detected FRBs that are repeating, as well as one that is definitely associated with a magnetar star. Perhaps all FRBs can be associated with such stars. Perhaps not.

But that is just the point. Perhaps one day we will be able to identify the origin of all FRBs and will know that they have a perfectly natural origin. Perhaps the search for alien life will have to begin afresh. But there is always that tantalizing hope, that slim possibility that one day a scientist rule out signal after signal that finally one will come in that defies alternative explanation. If all other explanations can be ruled out, we can say for certain that no natural source caused this.

Then, in the words of that great detective, we will have no choice but to accept the improbable. So these are some of the best candidates for signals from another planet, but even they come with massive strikes against them. We have not yet found a signal that conclusively points to the existence of aliens. But that is not to say that we never will. It's never aliens, right up until the moment where it is. 800 light years away, there's an unseen antimatter factory churning out high-energy positrons, tiny particles of antimatter that are streaming through the cosmos and colliding with our planet.

For much of history, we didn't know this strange source existed. Most of the positrons bombarding us went completely undetected, instead getting absorbed in our planet's atmosphere. It wasn't until we started looking from beyond the bounds of our planet that we noticed them. In 2011, NASA's Alpha Magnetic Spectrometer, a state-of-the-art particle detector some 200 miles up aboard the International Space Station, was switched on. What did it find? You guessed it.

Positrons. The presence of these subatomic particles was to be expected. but not in the numbers they were finding. Such was the sheer volume of positrons being detected that the usual sources like natural radioactive decay and cosmic rays no longer offered a sufficient explanation. So where were they coming from? We've only recently been able to trace the culprit of this cosmic antimatter shower, and it all comes down to another high-energy discovery.

A strange gamma ray haze named Gaminga, first identified in the 1970s. What is this mysterious source of gamma radiation? And what does it have to do with the unusual abundance of high energy positrons hitting our planet? I'm Alex McColgan and you're watching Astrum. Join me today as we tune into the enigmatic frequency of Gaminga, whose gamma radiation, has lit up the world of astrophysics for decades. In our night sky, nestled in the Gemini constellation in the northern celestial hemisphere, there is something peculiar going on.

In 1972, NASA's small astronomy satellite 2, or SAS 2, identified an unknown source of gamma radiation. But with the technology available at the time, the best it could do was trace its origin to this wider region of our Milky Way. So, the radiation's ultimate source remained hidden among the stars for decades. Nevertheless, it was given a name, Gaminga, as coined in 1976 by Italian physicist Giovanni Binyami, who would dedicate his career to studying it. It's a play on words, a combination of Gemini, the region where it's located, and Gamma, the type radiation it emits. Gominga is also a pun in Binyami's Milanese dialect, meaning it's

not there. A fitting name for a gamma ray haze with unknown origin. It wasn't until 1983, when Binyami and his team finally had their big break. They managed to identify a weak x-ray signal from Gominga using the Einstein X-ray satellite. This meant, although its exact position, remained unknown, they could narrow down their search area and were getting closer to uncovering Gominga's hiding place. But it didn't answer the big question, what is it, as astronomers could still only offer vague guesses about the true nature of the source. That was until 1991 when they had another lucky break. Two separate missions identified radiation coming from Gominga and they weren't constant signals.

but pulses. The first of these discoveries was made with a German-built X-ray telescope known as Rosat, short for Röhtgen satellite, named after the German word for X-rays. Rosat was the first to identify pulses in the X-ray signal coming from Gominga, and soon after, they were also confirmed in the gamma-wave lengths by the energetic gamma-ray experiment telescope, or Egrat, a telescope aboard NASA's Compton Gamma Ray Observatory satellite. Not only did these complementary observations demonstrate that the x-rays and the gamma rays were both coming from Gominga, but for the first time they revealed what Gominga was.

With a period of 0.237 seconds, flashing as it spins around its axis a little more than 4 Hz, or 4 times per second, Gaminga behaved like a pulsar. A pulsar is a type of neutron star that spins rapidly, emitting beams of radiation that sweep across space like a cosmic lighthouse. From across the galaxy, most pulsars appear to flash in radio waves, anywhere from a few times a minute to as fast as 700 times per second. And at this point in the early 90s, they were incredibly rare. You see, before Rosat and Eagret, only two other high-energy gamma-ray pulsars had ever been identified.

The Crab and Vela pulsars, and Crabb and Vela were different to comminger in a couple of key ways. First, in addition to gamma rays, both of these pulsars also produced radio waves, and were therefore visible using radio telescopes. So, if Gaminga was a pulsar, then it would be the first discovery of one that was apparently radio silent, only emitting enough radiation to be seen in the gamma and x-ray wavelengths. And second, Crabb and Vela were surrounded by their respective nebulae, remnants from when they were created from supernova explosions. But Gaminga's nebula was conspicuous by his absence. So why is Gaminga, this powerful source of gamma rays, so good at hiding from our radio telescopes?

Where is it nebula? Or could it be a different type of object altogether? Well, the answer to the first question is, in part, because we hadn't been listening properly, due to the limitations of the available technology and due to our understanding of the radio emissions of such stellar remnants. You see, while radio pulsars can emit radio waves across a wide bandwidth, from as low as 17 megahertz to above 87 gigahertz, around half the radio spectrum, not all of these frequencies travel well through space. Even though we've known since the 1970s that radio pulsars often peak between 100 to 200

megahertz, where they are intrinsically brightest, things like the interstellar medium, background, sky temperature and effects from the ionosphere mean that lower frequencies are dampened as they make their way across space, resulting in very weak signals that are much more difficult to detect. Because those radio signals are so weak, most radio telescopes hadn't been looking for them, instead confining themselves to search in for signals between 430 and 1,600 megahertz. This would have been fine had Gominga behaved as expected. for one of its kind. Since it did not, it took until 1997 for scientists to realize what was happening. Three independent observations from the Poshina Radio Astronomy Observatory were able to identify

extremely weak pulses from Gominga using a sensitive transit antenna. The faint radio pulses came in around 100 megahertz, which explains why previous radio searches for Gominga had come up silent. Turns out, Gominga wasn't truly hiding and had been sending us signals. We just weren't listening correctly. That same year, a team led by the late astronomer Janusz Gill theorized that another reason Giminga had appeared to be radio silent, maybe its magnetic field. Models showed that radio waves may be absorbed or refracted within the pulsars magnetosphere, leaving only weak pulses around 100 megahertz to be detectable.

This would effectively leave it quiet at the higher radio bands than most telescopes used. Confirminga was a pulsar, and specifically a gamma ray pulsar, was a big deal. In fact, 99% of its output is in the gamma range, making it one of the brightest gamma rays sources in our entire galaxy. It is, as it turns out, all that's left after a star several times. times more massive than our sun exploded about 350,000 years ago. But its relative radio silence and its apparent lack of a nebula weren't the only unusual things about this pulsar.

When Italian astrophysicists, including Bingami, Gominga's namegiver, compared a series of observations from the European Southern Observatory's 3.6-meter telescope and new Technology Telescope, with observations from the Canada-France-Hawaii telescope, they found that Gaminga was moving. Not only that, it was travelling at an unusually high speed of around 0.2 arc seconds per year. As a reminder, an arc second is a very small unit of angular measurement, use when we need more precise measurements than a degree would allow. Within each arc degree, there are 60 arc minutes, and within each arc minute are 60 arc seconds. These arc seconds are a common unit used in astronomy to talk about the movement of objects

across the sky from our perspective on Earth. If you were to draw a circle around the orbit of the moon around the Earth, there would be 360 degrees around that circular path. So at any given time of day or night, assuming nothing is blocking your view of the horizon, you can see about 180 degrees of the sky, and from the horizon to the zenith, the top of the sky is 90 degrees. If you hold out your little finger at arm's length and close one eye, the tip of your little finger covers about one degree of the sky roughly. Next time you're outside on a clear night, try this, and see if your little finger can cover the moon. It should, because the moon takes up only about half of a degree, or about

31 arc minutes in the night sky. Gaminga travelling 0.2 arc seconds across our sky each year may not sound like a lot, but from our perspective on Earth, the typical star only moves a few thousands of an arc second per year. Yet, despite being 800 light years from us, Gaminga will travel 30 arc minutes, the equivalent to the apparent diameter of the moon across our sky in just over 10,000 years. In other words, this stellar corpse is racing through the galaxy at nearly 210 kilometers per second. Heading towards the border between the constellations Gemini and Lynx, and at its current rate of motion, Gaminga will remain in Gemini for another half million years,

but it may need a new name after that. However, this mysterious pulsar gets stranger still. It is its vast speed that helps produce another feature that scientists were about to discover. As it hurtles through space, Gaminga leaves behind two ghostly X-ray tails that streak three trillion kilometers across the sky. As I discussed earlier,

despite the fact that this fast-moving pulsarer, is nearly radio silent, it certainly isn't quiet in the gamma-ray and x-ray wavelengths. In 1999, Issa's X-ray Multimuramission, or X-MM Newton, was launched to peer deeper into this X-ray universe, and four years later, a team led by Patrice Caraveo uncovered these comet-like X-ray trails. Their shape and brightness are partly explained by the shockwave created by the shockwave by Gominga's motion through space and its rotation as a pulsar, but they are also revealing of another attribute, Gominga's colossal mass.

Measuring only about 20 to 30 kilometers across, Gaminga is extremely dense, containing about as much mass as one and a half of our suns. To put that in perspective, if you had a teaspoon of neutron star material, it would weigh about 4 billion tons, as much as 10,000 Empire State buildings. As this dense, high mass object races forward through the low density interstellar medium, just 0.06 to 0.15 atoms per cubic centimeter, it compresses the interstellar medium and its own embedded magnetic field by a factor of 4. Meanwhile, the incessant spinning of the neutron star creates an environment.

an environment where electrons and their anti-matter counterparts, called positrons, can be accelerated to extreme energies, powerful enough to emit high-energy gamma rays. While most of these electrons are seen in the gamma radiation that escapes from the pulsar, some get trapped and spiral within this enhanced magnetic field. In these images from a computer model, the tails can be seen streaking along the edges of Gominga's three-dimensional shockwave, like the wake created by a boat going through water. Only this boat is more massive than our sun, and the wake is made up of extremely high-energy x-rays.

But the final piece of the Gominga puzzle wasn't discovered until 2005. It's nebula. Taking the form of a shell of neutral hydrogen gas, with a radius of 0.4 parsec wide, it took turned out to be what we call a pulsar wind nebula. This type of nebula is created from the wind plasma that emanates from a pulsar's magnetic poles. The plasma made of charged particles that can be accelerated to near light speed surrounds the pulsar, creating a nebula of high energy particles that give off strong X-ray emissions.

With the confirmation that Gaminger did have a nebula, its identity as a pulsar could finally be confirmed, but Chandra went even further. In addition to imaging Gominga, Chandra also looked at a second pulsar called B0355 plus 54, and by comparing the two, astronomers uncovered another possible explanation for the absence of radio pulses from Gaminga. On the surface, these pulsars seem quite similar. They are both about half a million years old, and they spin about four to five times per second. However, as you know, Gaminga is seen primarily in gamma ray pulses, with no bright radio

emissions. By contrast, the other pulsar, which I'll refer to as Pulsar B, is not seen in gamma rays, and instead is one of the brightest known radio pulsars. How could these two pulsars be so similar? so vastly different in how we see them. The answer may be as simple as how each of these pulsars are oriented relative to our observation from Earth. Astronomers believe that these images of Gominga and Pulsar B have revealed their spin axes

and uncovered a reason for why radio and gamma ray pulses may be present or absent on different pulsars. Like our own magnetic field around Earth, both of these pulsars have magnetic poles close to their spin poles. These poles are where the beams of pulsing radio emissions come from. You could try to model this if you skewer a little foam ball right down the middle. The foam ball is a pulsar, and the radio beams coming from the poles are represented by the wooden skewer coming out both ends.

If you spin the ball around the skewer like a spin axis, you create an equator around the middle. To illustrate the gamma ray source along the spin equator, called the Taurus, you could cut a hole in a paper plate and squeeze it over the foam ball. Now you've got yourself a disc of gamma rays beaming out from the equator in every direction. With Gaminga, the edge of the paper plate is pointing towards us, meaning the gamma rays are heading to Earth. But for Pulsar B, its relative position to us is at a different angle, as if looking at the

flat surface of the plate. The gamma rays are moving perpendicular to our line of sight, therefore missing Earth. Let's look again at the two Chandra images of Gumminga on the left and Pulsar B on the right, along with artist illustrations of what astronomers believe the Pulsar wind nebulas look like for each of these. In the image of Pulsar B, the long trailing blue tails represent the radio jets emanating from its poles, and the skewers coming out of both ends. Only, instead of being straight like a wooden skewer, Pulsar B is moving so fast through

space that these jets appear bent backwards, trailing behind as the Pulsar moves through space. Now look at the image of Gaminger. Here, the long twin tails on either side of the image are the radio jets, trailing behind as it too rushes through space. But this time, instead of pointing almost directly toward and away from our vantage point on Earth, these jets appear to be coming off to the sides, not aimed at Earth. So when astronomers look at Gominga, they see powerful gamma-ray emissions from the spin equator, but the radio jets point to the sides and remain unseen.

And when they look at Pulsar B, the opposite happens. The radio jets are pointed almost straight toward our planet, while the gamma-ray source at the equator is missing Earth. Sometimes, the most simple explanation is the correct one. And that finally brings us back to the decades-long mystery of an unusual abundance of antimatter bombarding our planet. For more than a decade, a particle detector called the Alpha Magnetic Spectrometer, or AMS2, has been attached to the International Space Station, collecting information on antimatter,

dark matter, and cosmic ray sources. As a reminder, cosmic rays are energetic. particles, fragments of atoms that travel through space at nearly the speed of light. These can be made by the Sun, by supernova explosions, or other cosmic means. And in 2013, the first results of the AMS2 experiment were announced. The detector had recorded more than 400,000 positrons, the largest sample of cosmic ray positron data ever collected, and increasing the world's total cosmic ray positron data by a hundredfold.

For years, many astronomers and physicists hope that this excess antimatter may be the byproduct of a dark matter annihilation, offering possible clues about this mysterious substance. After all, dark matter could make up around 27% of the cosmos, and yet we still don't know what it is. Like regular matter, dark matter holds mass and takes up space, but it doesn't seem to absorb, reflect or interact with light, at least not in a way we can detect. Some theorize that dark matter may be made of yet unidentified types of particles. Whatever it is, scientists had high hopes that the overabundance of antimatter being detected

aboard the ISS may hold clues about dark matter's true nature. Unfortunately, they've been left disappointed. The more scientists dig into the data, the clearer it's becoming. most likely source of these positrons may actually be pulsars. Astrophysicists had long suspected this, but until 2017, there simply wasn't proof. It was the high-altitude water Cherenkov gamma-ray observatory that finally added evidence to this hypothesis. A small halo of gamma radiation was identified surrounding Gominga with trillions of times

more energy than is visible to our eyes. 5 to 40 trillion electron volts, the sort of radiation usually produced by positrons. This was the first real observational evidence pointing to a pulsar as a potential source. Pulsars naturally surround themselves with a haze of both electrons and their positron counterparts as a result of the star's intense magnetic field. This intense magnetic field pulls particles from the pulsar's surface and accelerates them to near the speed of light. Scientists think that these accelerated positrons and electrons are then colliding with starlight, boosting the light to higher energies, which then radiates as the gamma ray halo observed.

But based on the size of the halo that the Hawke team saw, Gaminga's positrons would rarely have the energy required to reach our planet, and so they believed the excess positrons must have a more exotic source. That was until stunning new information was uncovered a few years later. thanks to a team led by astrophysicist Matea Di Maro. Using a decade of gamma-ray data from Gominga, acquired from Fermi's large area telescope, which is able to observe lower energy light than the Hawke gamma-ray observatory, the Maro's team was able to subtract out all other gamma-ray sources to reveal a spectacular glow

coming from Gominga, much, much bigger than what the scientists had ever seen before. The vast oblong halo of glowing gamma rays at an energy of 10 billion electron volts spanned 20 degrees of the sky, similar to the area the big dipper constellation occupies. And that's not all. The glow of gamma radiation is even bigger at lower energies. If we could see it all with the naked eye, Gaminga's gamma ray glow would dominate our sky, covering an area 40 times bigger than the full moon. With this new information, astrophysicist found that the size of Gominguez halo meant that this one pulsar alone could be responsible for as much as 20% of the excess positrons detected near Earth. From there, it's no stretch to

imagine that other pulsars are the most likely culprit for the remaining antimatter abundance we found. This explanation may not have solved the mystery of dark matter, but it is certainly a magnificent revelation. It was Jocelyn Bell B'anel, who discovered the first pulsar in 1967, back when people thought that those regular signals could be the work of extraterrestrial life. In the nearly 60 years that have passed since, we have found thousands of pulsars, and our understanding of these neutron stars has grown with every one. And since Gominga was identified as only the third known gamma ray pulsar in 1991, we've now spotted over 300 thanks to NASA's Fermi mission.

But given Gominga's track record of defying expectations and furthering science, I like to think that this particular pulsar has more secrets still to reveal. I'm happy to announce we have a weekly newsletter to keep up with all the discoveries in our cosmos, and our designer Peter has made the most beautiful email you'll ever receive. Sign up with the link down below. It's the best way to stay connected between videos. Short, focused updates on what's new and fascinating in space each week. No spam, no filler, just the good stuff.

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