Solar Superflares and Gondwana's Legacy: Unpacking Earth's Cosmic Changes

This is Space Time, Series 29, Episode 113, for broadcast on the 21st of September, 2026. Coming up on Space Time, new evidence of super flares on the Sun, how Gondwana changed life on planet Earth, and the incredibly shrinking planet Mercury. All that and more coming up on Space Time. Welcome to Space Time with Stuart Garry. A new study has found that a giant sunspot observed back in 1947 had the potential to trigger a massive solar superflare. Now, we all know the sun's capable of some massive eruptions. Solar flares and chronal mass ejections repeatedly hurl billions of tons of particles and radiation into space. This solar bombardment can be dangerous for life here on Earth. It can destroy technical infrastructure, damage satellites, disrupt navigation and communication systems, cause massive power blackouts over wide areas, and subject astronauts in space and even people in high-flying aircraft to high doses of radiation. The Sun offered its most impressive demonstration of its strength back in 1859. The solar storm which struck Earth during the Sircord Carrington event was so strong, the auroral lights, normally confined to higher latitudes, were clearly visible in the tropics. There wasn't much in the way of electrical circuits at the time, but there were telegraphs, many of which were short-circuited, and the operators working them electrocuted. Now, as we reported in last week's show, there have been hints of far bigger events through history, recorded through ancient tree rings. but as far as we know, nothing for hundreds of years. But now a new look at a massive sunspot recorded back in 1947 has raised some interesting questions. And the biggest is could this event have triggered a super flare, an event so violent it would have had more energy than trillions of hydrogen bombs? Now so far such powerful blasts have only ever been observed directly on distant stars, never on our own sun. But now astronomers from the Max Planck Institute and the University of Colorado have been exploring this observation in a detailed study reported in the journal Philosophical Transactions of the Royal Society A. The amount of energy the Sun releases during your average solar flare can be measured directly only outside the Earth's atmosphere, using high-flying balloons or spacecraft. But both have really only been possible from the beginning of the space age about 70 years ago. And in those 3 score and 10 years there's been no super flare action. The study's lead author Natalie Krivova from the Planck Institute says there's some evidence to suggest that the Sun too can produce super flares. And these clues can be found by looking at other sun-like stars. In late 2024, Krivova and colleagues were able to show that super flares occur roughly once a century on stars that resemble our Sun in key characteristics, such as similar metallicity, luminosity and mass. So the authors analysed data collected by NASA's Solid Dynamics Observatory spacecraft between 2010 and 2016. They correlated the amount of energy released by the 300 strongest solar flares during this period and compared that with the size of the corresponding active region the flares came from on the Sun's visible surface. Active regions are areas on the Sun's surface where the magnetic field is especially strong and complex in structure. They're associated with sunspots, dark areas on the Sun's visible surface that are cooler than the rest of the surface and are considered the potential starting points for solar eruptions. Graverbus says while no superflares occur during the observation period, the statistical relationship found between the release of energy and the size of an active region should also hold true for more powerful events. And that's when they turn their attention to the largest sunspots ever seen on the Sun. Now, sunspots have been systematically and regularly recorded on the surface of the Sun over the past 400 years. And they offer astronomers a way to look back through the Sun's history. So using their new comparison chart, based on the size of the sunspot, the authors were able to infer the size of the associated active region, and thus the strength of a possible eruption. And that's where the massive sunspot of April 1947 comes in. It covered some 0.6% of the visible solar disk, or to put that another way, its diameter was about 40 times that of the Earth's. Now, there was no super flare at the time, but the study shows that a sunspot of this size could have triggered a super flare. Provova says it shows the Sun has super flare potential. She says it can produce massive sunspots that, in principle, can serve as the starting point for some of the most extreme bursts of radiation. Has such a super flare ever actually occurred on the Sun? Well, for now at least, that remains one of our local star's mysteries. This is Space Time. Still to come, how God wanted to change life on planet Earth, and the incredibly shrinking planet Mercury. All that and more still to come on Space Time. A new study has rewritten the evolution of one of planet Earth's greatest ancient landmasses, the supercontinent Gondwana. The new research, led by Bill Collins from Curtin University, shows Gondwana was far larger than previously recognized. Using geochemical isotope comparisons that allow scientists to identify the age and origins of rocks deep beneath the planet's surface, Collins and colleagues identified vast regions stretching through Asia that were once part of this larger, greater Gondwana. Collins says the new work's reshaping cites his understanding of one of Earth's most important ancient landmasses. He says the findings could also help explain the dramatic environmental changes which paved the way for complex life to develop on Earth. You see, Gondwana's formation triggered profound global changes, including shifts in climate, in atmospheric chemistry, and in geological processes that ultimately helped create the conditions for what we call the Cambrian Explosion of Life. And that changed everything. The Earth is divided up into these tectonic plates, sort of rigid blocks and crusts. And there's maybe just over half a dozen of those plates. And the reason why they move around the Earth, and because of them we have earthquakes and volcanoes, which everyone knows about. But the reason why they move around is because the mantle underneath and the plates are these They're about 30 to 100 kilometres thick, depending on where you are. And they sit on a mantle which flows very, very slowly, but it flows nonetheless. So fake tectonics really is a response to convection of the mantle beneath. And so, as you would be aware, they float around on the surface, but the surface is a sphere. And so what happens through time is that all these continents come together at one particular time, but then they break apart again. and move around and tend to meet on the other side of the planet. So, plate tectonics is a response to the mantle convecting, and because the Earth is a sphere, the continents bang into each other to form a supercontinent every now and again, and that's probably every 500 or so million years. And Gondwanda was one of these supercontinents. Yeah, Tangier was the one that formed about 300 to 200 million years ago. And the one that formed before that was Gondwana. And Gondwana formed as a supercontinent between about 550 and 500 million years ago. That's interesting because that's about the same time as the Cambrian explosion in life, isn't it? Oh, bang on. Exactly the time that the Cambrian explosion of life happened. And that saw life diversify to the multi-celled plethora of existence we have today. Yes, yes, definitely. At that time, the limited animal that did exist, they tended to be soft-bodied creatures, no backbone, and they had very limited ability to evolve because the conditions were very harsh leading up to the formation of Kronmata. But once Kronmata formed, at least in our mind, things became a lot easier. for life to explode, and it did. Now, you've been looking at just how extensive Gondwana was. What have you found? Gondwana's been known about for over 100 years. In fact, it goes back to about the 1880s. This guy, Edward Zeus, realised that fossils that could be found in India were found in Australia and Antarctica, South America, Africa, and it made him think that there was a supercontinent, and he called it the Great Southern Continent. So that was the beginning of understanding it. But over time, and maybe... towards the end of the last century, people started to add a bit to this core, this continental core. And so they were seeing bits of Eastern America and bits of Europe and bits of Southern Asia like Pakistan, Iran, and even Turkey as being part of it. So although there was the core, there were these little bits around what at the time was the edge that had been added. And when they calculated up the percentage, of landmass that Gondwanas seemed to be, they said it was around 64%. And some guy had arbitrarily said that it is 75% of landmass, total landmass, excluding oceans, to produce continents. And so people then started turning around and saying, well, maybe Gondwana isn't really a supercontinent. because it's not big enough. That was a state of play until quite recently. Yeah, there's one of those in every group, isn't there? Well, it did cause a lot of problems because the thing about Gondwana is there's all these isotope proxies. Now, isotopes of different elements are used as proxies for all sorts of things. And the reason why we know about past climate is because of carbon isotope changes and oxygen isotope changes. And there are other elements that have the same sort of capacity. Another one is strontium, which records seawater compositional changes. And there's even one in rock and granite. And all of those isotopes were showing us that Around 550 million years ago, everything changed. And it's the biggest change that you're actually seeing in the isotopic record can be measured back to 4,000 million years. This is the biggest switch. So to me, there was always this paradox of why does Godwina have this really big switch? in all these proxy systems that record dynamic change in the Earth. Why do they all have this big switch around 550, 500 million years ago if gone one and one for the supercontinent? And so that was always in the back of my mind as a paradox. There's always a problem when... You start putting arbitrary lines in things instead of seeing the grayness between one genre and another. I can't agree with you more. Until you hit the nail on the head, there's always gray areas between what people classify as an artificial thing and what is reality. There's always transition, gray areas. So you looked at different isotopes and ratios to work out exactly what was where. And from that, you were able to determine that Gondwanda was much bigger than some estimates had placed it at. This isotopic system that we use is called samarium neodymium. Samarium breaks down the form neodymium. It's a parent-daughter type isotope system. It's rare earth. is one that's very robust. It can survive temperatures of resetting that might tend to 1,000 degrees centigrade. So it holds the information that's sending back to its origin. So it doesn't get destroyed by volcanic activity and things like that, which is, what, 800 degrees? Yeah, exactly. And so I was just going to say, like, underneath Every volcano is a magma, which is usually composed of granite, particularly on the continent. And if you looked at the Himalayas today, for example, there are granites in the Himalayas that are 20 million years old. There are others that are 50 million years old, others that are 100 million years old, and so on. But they all extend back until 500, 550 million years ago. And that's what the barium, neodymium isotopic composition tells us, that they all come from this material, which is about the age of what we thought Gondwana was when it formed. The link between Greater Gondwana and ending Snowball Earth. Snowball Earth was 717 million years ago. I know that because I just did a story on it. It went for over 100 million years. It was a very, very long period of time that Snowball Earth existed. And the thing about Snowball Earth, it defines that all the continents were covered in ice, that it didn't matter whether or not they were at the poles or. At the equator. Snowball Earth actually continued for at least 100 million years, up to maybe 580. People argue about when it stopped, but certainly there was a time between 500 and... 600 million years when we started coming out of Snowball Earth. And it does coincide with when Gondwana was forming. And most of it had formed between about 600 and 700, but we know that it kept forming until about 550. And when Gondwana was a supercontinent, as it finally came together, Snowball Earth did persist up to about that time when it changed, which was around the time that Gondwana. How did Gondwana change our climate? The critical thing was all these fragments that went to form Gondwana, all the big continental landmasses came together between 600 and 500 million years ago, forming a huge mountain range that crisscrossed Gondwana land, a little bit like what the Himalayas are today. But like the Himalayas, they don't erupt volcanoes from them. Large mountain belts don't do that. So when Gondwana formed and all these big mountain belts existed, the mantle of the Earth had to convect. And so the way that it did it, it reconfigured itself to start producing volcanoes around the edge of Gondwana. And this was the first ring of fire. I'm sure you know about the Pacific ring of fire. Yeah, I've been watching Krakatoa very closely, or should I say Anak Krakatoa these days? That's right. Well, Krakatoa is just on the edge of this, because that's Indonesia, and it's really complicated up there geologically. But that's part of this ring. That ring started right after Gondwana formed, and it's continued today as the Ring of Fire. And the important point about that is, Unlike the mountain ranges that don't have volcanic activity, the volcanoes that went around the Pacific at the time released huge amounts of CO2 and water. The estimate today for the amount of water that comes out daily out of the Earth through volcanoes into the atmosphere is between 1 to 4 million metric tonnes of water every day. And CO2 is 300 to 400,000 metric tonnes every day. If that went on every day for 50 million years, you're going to change the climate from snowball earth ice house into a greenhouse. And that greenhouse condition that emerged in the Cambrian after Gondwana formed was the reason, I argue, that the climate changed into a habitable landmass that animals could evolve on. And that is what the Caribbean explosion was. What were the last bits to come off? Around Australia, it's an interesting story. The Latvia, which is basically an underwater continent, the eighth continent of the world, recognized only 20 years ago. A fragment of Australia that broke off around 90 million years ago and floated out into the Pacific Ocean to form, of course, the Tasman Sea in between. That split off from what was the edge of Gondwana. And so Zealandia, which is North and South Island, plus Campbell Plateau below that and a few other things to the north, like Lord Howe Island is another. New Caledonia, yeah. Yes, all that was actually off the edge of Gondwana. And so the southern part was connected to Antarctica at the time and the northern part to Australia. But Australia broke off around 43 million years ago, 45, 43 million years ago. That's Professor Bill Collins from Curtin University. And this is Space Time. Still to come, the incredibly shrinking planet Mercury and a new study has found that 2025 was one of the driest years in the past three decades. All that and more still to come on Space Time. A new study suggests that the planet Mercury may have shrunk by as much as 30% since its creation. The findings reported in the journal Geophysical Research Letters shows how the nearest planet to the Sun may have lost up to 23 kilometres of its total diameter since the planet first formed. Mercury's surface is riddled with craters, ridges and steep cliffs, evidence of a once larger planet that has shrunk over time. Like the other terrestrial or rocky planets in our solar system, Mercury was formed by a flurry of violent collisions between planetesimals and asteroids orbiting the Sun around 4.6 billion years ago. And the energy from these impacts generated huge amounts of heat, which the planets slowly lose over time. That includes Mercury. And like a balloon left out in the cold, Mercury's interior has shrank as it cooled. And the outermost rocky layers compensated for this planetary shrinkage by crumpling and cracking to form tectonic features like scarps and ridges. The degree of shrinking is important for helping scientists infer key features about Mercury's interior and evolution. The study's lead author, Gaku Nishiyama from the German Aerospace Center DLR, says more shrinking means Mercury could have a larger metallic core and less light elements like silicon mixed into the metal core or a higher starting temperature. Cooling should shrink a planet fairly evenly, making wrinkle features known as shortening structures similarly common everywhere. But the formation of new impact craters creates depressions and covers the landscape with debris, making the surface rougher and rendering signs of shrinkage harder to spot among the billions of years of geological development and evolution. So Nishiyama and colleagues combined previous maps of geologic evidence for contraction on Mercury with new maps of roughness for the entire planet's surface, a measure of how lumpy the landscape is. For the first time they were able to show that the roughest areas on Mercury had fewer visible wrinkles. Nishiyama says that suggests that impact debris on rougher areas could be covering up the shrinkage wrinkles, so like freshly added gravel hiding ruts in a road. So the authors used the contraction required to form shrinkage ridges and scarps in less disputed areas to estimate how much contraction likely occurred planet-wide, including that under the rough patches. They found that missing features in rough areas could amount to some 20-30% more shrinkage over Mercury's lifetime. That means a total shrinkage of up to 23 kilometers in the planet's diameter, rather than the previously estimated 4 to 16 kilometers. And Nishiyama says these updated figures could still be an underestimate. Existing Mercury data from NASA's MESSENGER mission, which ended in 2015, can only be reliably used to measure features larger than about 5 kilometers. Across. In November, the joint European-Japanese BepiColombo mission will arrive at Mercury, only the third spacecraft ever to visit the planet. And by April next year, it'll begin collecting much higher-resolution scans of the Mercuryan surface. And these should reveal scarps, ridges and impact craters in far more detail than ever before, thereby giving us an even better picture and a better idea of how much shrinkage Mercury's undertaken. This is Space Time. And time now to take a brief look at some of the other stories making news in science this week with the Science Report. Scientists have found that around a third of the ward's population are being exposed to second-hand smoke, potentially contributing to nearly 1.7 million deaths annually. The findings reported in The Lancet estimates that 2.71 billion people globally are exposed to second-hand smoke every year, including 767 million kids under the age of 14. The authors looked at the impacts of secondhand smoke across 204 countries between 1990 and 2023, finding that women and children experienced the biggest impacts, with the Oceanic, Southeast Asia and Eastern Asian women being 59% more likely to be exposed than men. Lung infections were the leading issue in exposed children, but heart disease was by far the greatest issue for people across all ages. New figures show that de-radicalization programs designed to counter violent extremism, such as far-right neo-Nazi ideology and radical Islam, have basically failed. The figures by the Australian Department of Home Affairs show that out of 292 extremists that completed the $ 75 million federal government program, 227 showed no change in their support for violent terrorist ideology. And 24 actually became more dangerous. In fact, only 23 out of the 292 have peed to have become some degree less extreme in their views. The findings are reflecting similar failures in similar de-radicalisation programs right across Europe. The news comes as Mike Burgess, the head of the Australian security and intelligence organisation ASIO, says the spy agencies fought 16 terrorist plots in Australia over the last nine months since the Bondi Beach massacre. Fifteen people were killed and 41 injured by Islamic State-inspired Muslim terrorists during celebrations at the iconic beach's Archer Park on December 14 last year. A new study has found that 2025 was one of the driest years in the past three decades. The latest World Meteorological Organization report on the state of the world's water has revealed that rivers right across the globe have had one of their driest periods in more than 30 years, continuing a long-term drop in Earth's freshwater storage and an acceleration of glacial melting. However, parts of northeastern and eastern Australia barked the trend, with river flows above average. Globally, these trends have big implications for people and economies in the future. The report also found the water cycles becoming more erratic and unpredictable, swinging between too little or too much. And the past seven years has seen the fewest rivers with what's called normal flows since 1991. The study also highlighted groundwater shortages in parts of southern Australia, but found eastern Australia had above-average groundwater levels. The authors found that Asia and Africa are the regions most affected by water-related disasters. It was this month in 1937 that the world's last known Tasmanian tiger or thylacine died in the Hobart Zoo. The animal's passing marked the extinction of its species. The thylacine was Australia's largest marsupial predator. It basically looked like a dog, but with distinctive stripes and a jaw that could open up to 80 degrees, one of the largest gapes of any mammal. The thylacine fed primarily on small mammals and birds. It was nocturnal and shy, and was seldom seen by humans. However, beginning in the 19th century, farmers and politicians wrongly blamed the poor creatures for livestock deaths actually carried out by wild dog packs, and spurred on by a bounty offered by government, hearted them relentlessly. Attempts at protecting the species in the wild came much too late. And despite numerous unconfirmed sightings in recent decades, no definitive sightings of the thylacine have occurred since the late 1930s. A sad chapter in Australia's already abysmal native wildlife record. One of humanity's most evil manifestations, the Nazis, are trying to make another comeback, this time through a viral AI-generated TikTok video depicting their deranged Fuhrer standing in Antarctica at the gateway of Agartha, the hollow earth of old pagan and ancient beliefs. Of course, Nazis aren't that bright, and the cold weather of Antarctica would not have been a good idea for the little corporal, whose DNA evidence shows Hitler already had an undescended testicle and a genetic condition linked to having an unusually small penis. The cold weather would have done none of that any good. But the absurd image does make sense to white supremacists. They're trying to push the myth of Agartha as being the real home of the Third Reich's Aryan race, an invention created by the occult mad SS. Skeptic's Tim Mendham says the video is full of coded, explicit far-right messages fused with pop-cultural references designed to suck in the gullible and impress the weak-minded. The hollow earth theory has been around a while. One of the more interesting ones was a fellow who first claimed to have flown over the North Pole, Richard Byrd and his pilot friend. He probably didn't. He probably lied about it. The story goes that he actually hadn't gone long enough to have actually flown over the North Pole. But he went. He later went and claimed he flew into the hole at the South Pole and saw lots of aircraft and things that was taken down to meet the creatures of the leaders down there. So I think Bird might have been up for the ferries. But anyway, therefore, Hollow Earth has been around a while. There's another guy who had an expedition to go and find a hole in the top of the Earth. And he was walking along, hiking along, and came to a fence and said, no trespass. And so he went back. He's not a very dedicated explorer. Anyway, recently, and thanks to sort of social media and AI generation of videos and that sort of stuff, there's a revised or revivified belief in something called Agatha, A-G-A-R-T-H-A, which is the country, if you like, within the earth. And that one of the set of people who live there are Aryans, Nazis in particular, and that they moved down there when they were losing the war, Second World War, and they've been living there ever since. So it's become a bit of a cult it's a agartha thing there's a lot of videos out there apparently some of them use the song down under by men at work which is a bit rude i feel that people at men at work love the idea of that it's obviously created as ai videos from totally phony backgrounds they drink a thing called white monster energy drink which is popular with the species living in agartha it's A strange situation that has been going around. It was going around from Bird, who was in the 20s or something like that, who was making this claim. Edgar Rice Burroughs had stories set inside the hollow earth, and various other people have been making the idea, making a claim. There was old satellite photographs which showed a big hole where the North Pole was, which was actually an artifact of the series of photos put together. The satellite wasn't able to take a photo of the top of the pole, probably at the wrong angle, but it looked like a hole at the top. a bit like a death star with a hole at the top of it or something. And so it's been going around for a while, but it's had a bit of a revival lately. It's been hard to say whether they're actually neo-Nazis themselves who are making the claim, but I'm never quite sure exactly why you would want to claim about a civilization in the middle of the Earth, or at least under the Earth, under the ground. The hollow Earth never seems to be all the way down to the bottom. It would be a bit hot. It seems to be like a big cave. underneath the surface of the Earth. So most of it's sort of rubbish, but people hijack sort of silly ideas and they then start using them as if they're real. And they're starting to drag people in. They're using Roblox and that sort of stuff. Roblox used to be a game, but getting sort of people signed up to such things and they can become a funnel to get people to believe in sort of radical ideas and that sort of stuff and also get names and Figures and copies that are financial scams and all that sort of stuff. Yeah, that's your build-up contact lists for scamming people and pushing off an Aryan viewpoint. That's right, yeah. There's a synthesis side to it where a lot of people are actually using it to get people involved. And that's why in the skeptical world, some of these things just seem silly. But then actually there's an element of not-so-sillyness beneath them. And even the silliest things. People can twist that to their advantage, whether that's financial, power trip, whatever, to use some of the silly ideas and suddenly try and add some weight to them and drag people in. So almost in a skeptical world, there is no such thing as a silly idea that should not be sort of looked at closely to see if there's an element of nastiness about it. I was told people who follow Loch Ness are pretty harmless. I haven't seen any great conspiracies there. Bigfoot is starting to have some conspiracies associated with it of extraterrestrial parallel universes and time warps and things, and therefore they start to verge out away from their original intention. For this Legata thing, Hollow Earth has definitely had some pretty evil intents by some people involved in it. That's the Skeptic's Tim Mendham, and this is Space Time. And that's the show for now. 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