A strange bright burst in space baffled astronomers for more than a year. Now, they've solved the mystery
Around midday on 13 June last year, my colleagues and I were scanning the skies when we thought we had discovered a strange and exciting new object in space. Using a huge radio telescope, we spotted a blindingly fast flash of radio waves that appeared to be coming from somewhere inside our galaxy.
After a year of research and analysis, we have finally pinned down the source of the signal – and it was even closer to home than we had ever expected.
A surprise in the desert
Our instrument was located at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory in remote Western Australia, where the sky above the red desert plains is vast and sublime. We were using a new detector at the radio telescope known as the Australian Square Kilometre Array Pathfinder – or ASKAP – to search for rare flickering signals from distant galaxies called fast radio bursts.
We detected a burst. Surprisingly, it showed no evidence of a time delay between high and low frequencies – a phenomenon known as ' dispersion '. This meant it must have originated within a few hundred light years of Earth. In other words, it must have come from inside our galaxy – unlike other fast radio bursts which have come from billions of light years away.
A problem emerges
Fast radio bursts are the brightest radio flashes in the Universe, emitting 30 years' worth of the Sun's energy in less than a millisecond – and we only have hints of how they are produced.
Some theories suggest they are produced by ' magnetars ' – the highly magnetised cores of massive, dead stars – or arise from cosmic collisions between these dead stellar remnants. Regardless of how they occur, fast radio bursts are also a precise instrument for mapping out the so-called 'missing matter' in our Universe.
When we went back over our recordings to take a closer look at the radio burst, we had a surprise: the signal seemed to have disappeared. Two months of trial and error went by until the problem was found.
ASKAP is composed of 36 antennas, which can be combined to act like one gigantic zoom lens six kilometres across. Just like a zoom lens on a camera, if you try to take a picture of something too close, it comes out blurry. Only by removing some of the antennas from the analysis – artificially reducing the size of our 'lens' – did we finally make an image of the burst.
We weren't excited by this – in fact, we were disappointed. No astronomical signal could be close enough to cause this blurring. This meant it was probably just radio-frequency ' interference ' – an astronomer's term for human-made signals that corrupt our data. It's the kind of junk data we'd normally throw away.
Yet the burst had us intrigued. For one thing, this burst was fast. The fastest known fast radio burst lasted about 10 millionths of a second. This burst consisted of an extremely bright pulse lasting a few billionths of a second, and two dimmer after-pulses, for a total duration of 30 nanoseconds.
So, where did this amazingly short, bright burst come from?
A zombie in space?
We already knew the direction it came from, and we were able to use the blurriness in the image to estimate a distance of 4,500 km. And there was only one thing in that direction, at that distance, at that time – a derelict 60-year-old satellite called Relay 2.
Relay 2 was one of the first ever telecommunications satellites. Launched by the United States in 1964, it was operated until 1965, and its onboard systems had failed by 1967. But how could Relay 2 have produced this burst?
Some satellites, presumed dead, have been observed to reawaken. They are known as 'zombie satellites'. But this was no zombie. No system on board Relay 2 had ever been able to produce a nanosecond burst of radio waves, even when it was alive.
We think the most likely cause was an 'electrostatic discharge'. As satellites are exposed to electrically charged gases in space known as plasmas, they can become charged – just like when your feet rub on carpet. And that accumulated charge can suddenly discharge, with the resulting spark causing a flash of radio waves.
Electrostatic discharges are common and are known to cause damage to spacecraft. Yet all known electrostatic discharges last thousands of times longer than our signal, and occur most commonly when the Earth's magnetosphere is highly active. And our magnetosphere was unusually quiet at the time of the signal.
Another possibility is a strike by a micrometeoroid – a tiny piece of space debris – similar to that experienced by the James Webb Space Telescope in June 2022. According to our calculations, a 22 micro-gram micrometeoroid travelling at 20km per second or more and hitting Relay 2 would have been able to produce such a strong flash of radio waves. But we estimate the chance that the nanosecond burst we detected was caused by such an event to be about 1%.
Plenty more sparks in the sky
Ultimately, we can't be certain why we saw this signal from Relay 2. What we do know, however, is how to see more of them. When looking at 13.8 millisecond timescales – the equivalent of keeping the camera shutter open for longer – this signal was washed out, and barely detectable even to a powerful radio telescope such as ASKAP.
But if we had searched at 13.8 nanoseconds, any old radio antenna would have easily seen it. It shows us that monitoring satellites for electrostatic discharges with ground-based radio antennas is possible. And with the number of satellites in orbit growing rapidly, finding new ways to monitor them is more important than ever.
But did our team eventually find new astronomical signals?
You bet we did. And there are no doubt plenty more to be found. DM
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Daily Maverick
7 days ago
- Daily Maverick
A strange bright burst in space baffled astronomers for more than a year. Now, they've solved the mystery
The quest to pin down the source of the burst led to a derelict 60-year-old satellite. Around midday on 13 June last year, my colleagues and I were scanning the skies when we thought we had discovered a strange and exciting new object in space. Using a huge radio telescope, we spotted a blindingly fast flash of radio waves that appeared to be coming from somewhere inside our galaxy. After a year of research and analysis, we have finally pinned down the source of the signal – and it was even closer to home than we had ever expected. A surprise in the desert Our instrument was located at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory in remote Western Australia, where the sky above the red desert plains is vast and sublime. We were using a new detector at the radio telescope known as the Australian Square Kilometre Array Pathfinder – or ASKAP – to search for rare flickering signals from distant galaxies called fast radio bursts. We detected a burst. Surprisingly, it showed no evidence of a time delay between high and low frequencies – a phenomenon known as ' dispersion '. This meant it must have originated within a few hundred light years of Earth. In other words, it must have come from inside our galaxy – unlike other fast radio bursts which have come from billions of light years away. A problem emerges Fast radio bursts are the brightest radio flashes in the Universe, emitting 30 years' worth of the Sun's energy in less than a millisecond – and we only have hints of how they are produced. Some theories suggest they are produced by ' magnetars ' – the highly magnetised cores of massive, dead stars – or arise from cosmic collisions between these dead stellar remnants. Regardless of how they occur, fast radio bursts are also a precise instrument for mapping out the so-called 'missing matter' in our Universe. When we went back over our recordings to take a closer look at the radio burst, we had a surprise: the signal seemed to have disappeared. Two months of trial and error went by until the problem was found. ASKAP is composed of 36 antennas, which can be combined to act like one gigantic zoom lens six kilometres across. Just like a zoom lens on a camera, if you try to take a picture of something too close, it comes out blurry. Only by removing some of the antennas from the analysis – artificially reducing the size of our 'lens' – did we finally make an image of the burst. We weren't excited by this – in fact, we were disappointed. No astronomical signal could be close enough to cause this blurring. This meant it was probably just radio-frequency ' interference ' – an astronomer's term for human-made signals that corrupt our data. It's the kind of junk data we'd normally throw away. Yet the burst had us intrigued. For one thing, this burst was fast. The fastest known fast radio burst lasted about 10 millionths of a second. This burst consisted of an extremely bright pulse lasting a few billionths of a second, and two dimmer after-pulses, for a total duration of 30 nanoseconds. So, where did this amazingly short, bright burst come from? A zombie in space? We already knew the direction it came from, and we were able to use the blurriness in the image to estimate a distance of 4,500 km. And there was only one thing in that direction, at that distance, at that time – a derelict 60-year-old satellite called Relay 2. Relay 2 was one of the first ever telecommunications satellites. Launched by the United States in 1964, it was operated until 1965, and its onboard systems had failed by 1967. But how could Relay 2 have produced this burst? Some satellites, presumed dead, have been observed to reawaken. They are known as 'zombie satellites'. But this was no zombie. No system on board Relay 2 had ever been able to produce a nanosecond burst of radio waves, even when it was alive. We think the most likely cause was an 'electrostatic discharge'. As satellites are exposed to electrically charged gases in space known as plasmas, they can become charged – just like when your feet rub on carpet. And that accumulated charge can suddenly discharge, with the resulting spark causing a flash of radio waves. Electrostatic discharges are common and are known to cause damage to spacecraft. Yet all known electrostatic discharges last thousands of times longer than our signal, and occur most commonly when the Earth's magnetosphere is highly active. And our magnetosphere was unusually quiet at the time of the signal. Another possibility is a strike by a micrometeoroid – a tiny piece of space debris – similar to that experienced by the James Webb Space Telescope in June 2022. According to our calculations, a 22 micro-gram micrometeoroid travelling at 20km per second or more and hitting Relay 2 would have been able to produce such a strong flash of radio waves. But we estimate the chance that the nanosecond burst we detected was caused by such an event to be about 1%. Plenty more sparks in the sky Ultimately, we can't be certain why we saw this signal from Relay 2. What we do know, however, is how to see more of them. When looking at 13.8 millisecond timescales – the equivalent of keeping the camera shutter open for longer – this signal was washed out, and barely detectable even to a powerful radio telescope such as ASKAP. But if we had searched at 13.8 nanoseconds, any old radio antenna would have easily seen it. It shows us that monitoring satellites for electrostatic discharges with ground-based radio antennas is possible. And with the number of satellites in orbit growing rapidly, finding new ways to monitor them is more important than ever. But did our team eventually find new astronomical signals? You bet we did. And there are no doubt plenty more to be found. DM
The South African
18-06-2025
- The South African
Winter solstice
The winter solstice marks the point when the Earth's axial tilt is farthest away from the sun in your hemisphere. Image: Pexels The winter solstice is the shortest day and longest night of the year, marking the point when the Earth's axial tilt is farthest away from the Sun in your hemisphere. It occurs once a year, around 20 or 21 June in the southern hemisphere. In the northern hemisphere, this same day is known as the summer solstice, as it's their longest day and shortest night. 🗓️ Date: Saturday, 21 June 🕓 Time: Approximately 22:42 At this time, the sun reaches its most northerly point in the sky relative to the southern hemisphere, and the region experiences its least daylight hours. The sun rises latest and sets earliest Daylight is at its shortest – roughly 10 hours or less in many parts of South Africa – roughly 10 hours or less in many parts of South Africa The sun appears at its lowest noon altitude in the sky in the sky After this point, days gradually begin to lengthen, signaling the slow return toward summer Colder mornings and nights: This is usually the peak of South Africa's cold, dry winter , especially inland This is usually the peak of South Africa's , especially inland Longer nights: Perfect for stargazing, since the skies are often clearer in winter Perfect for stargazing, since the skies are often clearer in winter Cultural observances: Some Indigenous African communities and spiritual groups mark the solstice with seasonal rituals or ceremonial gatherings Some Indigenous African communities and spiritual groups mark the solstice with or Agricultural relevance: Traditionally, it signaled the turning point for winter crops or preparation for spring planting In Cape Town , the sun will rise at 07:51 and set at 17:44 on the winter solstice , the sun will rise at and set at on the winter solstice The term 'solstice' comes from Latin solstitium , meaning ' sun stands still ', referring to the apparent halt in the sun's movement before it reverses direction , meaning ' ', referring to the apparent halt in the sun's movement before it reverses direction The June solstice marks the start of astronomical winter, though meteorological winter begins on 1 June Warm up with seasonal food : Winter solstice is a great time to cook hearty stews and enjoy hot beverages : Winter solstice is a great time to cook hearty stews and enjoy hot beverages Reflect or set intentions : Many cultures treat the solstice as a time for introspection , planning, or renewal : Many cultures treat the solstice as a time for , planning, or renewal Enjoy the stars: With longer nights and less cloud cover, it's an ideal time for observing constellations and planets Let us know by leaving a comment below, or send a WhatsApp to 060 011 021 1 Subscribe to The South African website's newsletters and follow us on WhatsApp, Facebook, X and Bluesky for the latest news.
Daily Maverick
30-05-2025
- Daily Maverick
X-rays have revealed a mysterious cosmic object never before seen in our galaxy
After the initial discovery, we began follow-up observations using telescopes around the world, hoping to catch more pulses. With continued monitoring, we found the radio pulses from ASKAPJ1832 arrive regularly — every 44 minutes. This confirmed it as a new member of the rare long-period transient group. In a new study published today in Nature, we report the discovery of a new long-period transient — and, for the first time, one that also emits regular bursts of X-rays. Long-period transients are a recently identified class of cosmic objects that emit bright flashes of radio waves every few minutes to several hours. This is much longer than the rapid pulses we typically detect from dead stars such as pulsars. What these objects are, and how they generate their unusual signals, remains a mystery. Our discovery opens up a new window into the study of these puzzling sources. But it also deepens the mystery: the object we found doesn't resemble any known type of star or system in our galaxy – or beyond. Watching the radio sky for flickers There's much in the night sky that we can't see with human eyes but can detect when we look at other wavelengths, such as radio emissions. Our research team regularly scans the radio sky using the Australian SKA Pathfinder (ASKAP), operated by CSIRO on Wajarri Yamaji Country in Western Australia. Our goal is to find cosmic objects that appear and disappear (known as transients). Transients are often linked to some of the most powerful and dramatic events in the universe, such as the explosive deaths of stars. In late 2023, we spotted an extremely bright source, named ASKAP J1832-0911 (based on its position in the sky), in the direction of the galactic plane. This object is located about 15,000 light years away. This is far, but still within the Milky Way. A dramatic event After the initial discovery, we began follow-up observations using telescopes around the world, hoping to catch more pulses. With continued monitoring, we found the radio pulses from ASKAPJ1832 arrive regularly — every 44 minutes. This confirmed it as a new member of the rare long-period transient group. But we did not just look forward in time — we also looked back. We searched through older telescope data from the same part of the sky. We found no trace of the object before the discovery. This suggests something dramatic happened shortly before we first detected it — something powerful enough to suddenly switch the object 'on'. Then, in February 2024, ASKAPJ1832 became extremely active. After a quieter period in January, the source brightened dramatically. Fewer than 30 objects in the sky have ever reached such brightness in radio waves. For comparison, most stars we detect in radio are about 10,000 times fainter than ASKAPJ1832 during that flare-up. A lucky break X-rays are a form of light that we can't see with our eyes. They usually come from extremely hot and energetic environments. Although about 10 similar radio-emitting objects have been found so far, none had ever shown X-ray signals. In March, we tried to observe ASKAPJ1832 in X-rays. However, due to technical issues with the telescope, the observation could not go ahead. Then came a stroke of luck. In June, I reached out to my friend Tong Bao, a postdoctoral researcher at the Italian National Institute for Astrophysics, to check if any previous X-ray observations had captured the source. To our surprise, we found two past observations from NASA's Chandra X-ray Observatory, although the data were still under a proprietary period (not yet public). We contacted Kaya Mori, a research scientist at Columbia University and the principal investigator of those observations. He generously shared the data with us. To our amazement, we discovered clear X-ray signals coming from ASKAPJ1832. Even more remarkable: the X-rays followed the same 44-minute cycle as the radio pulses. It was a truly lucky break. Chandra had been pointed at a different target entirely, but by pure coincidence, it caught ASKAPJ1832 during its unusually bright and active phase. A chance alignment like that is incredibly rare — like finding a needle in a cosmic haystack. Still a mystery Having both radio and X-ray bursts is a common trait of dead stars with extremely strong magnetic fields, such as neutron stars (high-mass dead stars) and white dwarfs (low-mass dead stars). Our discovery suggests that at least some long-period transients may come from these kinds of stellar remnants. But ASKAPJ1832 does not quite fit into any known category of object in our galaxy. Its behaviour, while similar in some ways, still breaks the mould. We need more observations to truly understand what is going on. It is possible that ASKAPJ1832 is something entirely new, or it could be emitting radio waves in a way we have never seen before. DM
