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Speaker 1: Welcome to BrainStuff, a production of iHeartRadio. Hey, BrainStuff. Lauren Vogelbaum here. Sunspots. The ancient Chinese referred to them as stars inside the solar orb. One Renaissance astronomer argued that they were actually undiscovered planets. Today, some believe their appearance is linked to waves of UFO sightings and paranormal activity. The rest of us wonder if they're the reason for our dropped calls or spotty radio or internet service. Sunspots are the peculiar dark spots that pop up regularly on the surface of the sun. They usually appear in pairs or in groups called belts on either side of the sun's equator, between about 40 degrees and 50 degrees latitude both north and south. Sunspots vary tremendously in size, ranging from Less than 200 miles across, that's 30 kilometers, to many times larger than Earth. Small sunspots may last for less than an hour, but larger ones can last up to six months. Some are big enough to be seen by the naked eye. Keep in mind, of course, that staring directly at the unfiltered sun is an extremely bad idea because it can permanently harm your eyes. Side note here, yes, seriously. You can observe the sun and its spots safely by using solar viewing glasses or eclipse glasses. Or if you have a telescope or binoculars, you can fit them with a specialized solar filter meant for observation. Or if you don't have any of those on hand, you can always use a pinhole projector. Punch a hole in a stiff piece of paper and with the sun at your back, project an image of it onto another surface like a wall or another piece of paper. Do not mess around with the sun. it will win. Anyway, sunspots appear dark to us when viewed safely because they're cooler in temperature than the surrounding areas on the sun's visible surface. This is called the photosphere, and it has a temperature of about 10,000 degrees Fahrenheit, or around 5,500 Celsius. The dark interior of a sunspot can be about 40% cooler than the rest of the sun's surface. Sunspots are cooler because they're areas of intense magnetism, so intense that it inhibits the flow of hot material from the sun's interior to its surface. Sunspots occur because the sun isn't a hunk of rock like Earth, but a ball of continually circulating plasma, that is, hot electrically charged gases, that doesn't move in one piece. The interior and exterior of the sun rotate separately. And the exterior rotates more quickly at the equator than at the north and south poles. A point on the equator will only take 25 Earth days to go around, while a point near one of the poles could take 36. Over time, all of that messy and uneven movement twists and distorts the sun's main magnetic field in the same way that your bedsheets get wrinkled and bunched up when you toss and turn in your sleep. The bunched-up spots, the twists in the magnetic field lines, have so much magnetic power that they push on the circulating plasma beneath them and prevent its heat from rising directly to the surface. In other words, they become sunspots. The cooler sunspots appear darker, and the plasma blocked by them will flow into the areas surrounding them, making those even hotter and brighter than normal, thus making the sunspots stand out even more. I should say here that sunspots are still objectively very bright, about as bright as the full moon. The average sunspot is about as big as our planet, but the biggest on record, which appeared in 1947, was about 18 times as large as the whole surface area of the Earth. Due to the size of the sun, despite the slow speed of its surface rotation, a sunspot will appear to move across its surface about four times faster than a point on Earth would appear to move from space. In London, the Royal Observatory Greenwich has kept detailed records of the size and location of sunspots since 1874. Roughly every 11 years, the number of sunspots increases from nearly zero to more than 100, then decreases to near zero again as a new cycle starts. This pattern is called the sunspot cycle. Since the 1700s, sunspot cycles have varied in length between 9 and 14 years. At the beginning of the cycle, sunspots form in the sun's mid-latitudes, but as the cycle progresses, they occur closer to the equator. We think the cycle occurs because the sun contains a sort of conveyor belt that circulates plasma between the sun's equator and its poles and then back again over a period of years. The idea is that when sunspots that formed early in a sunspot cycle begin to decay and They leave a kind of magnetic imprint on the moving plasma beneath them. The conveyor belt carries that plasma with those magnetic imprints towards the poles and then back inside the sun. The magnetic fields within the sun are then distorted and intensified even more before the conveyor belt sends the plasma to resurface nearer the equator. There, the plasma forms new, even more powerful sunspots. During any given sunspot cycle, activity usually rises quickly and then declines gradually. The point where sunspots reach their peak of intensity is called the solar maximum, and the low point the solar minimum. Solar minimums usually last for several years, but they sometimes go on for much longer. For example, there was a 60-year period between 1650 and 1710 when there was little or no sunspot activity at all. This is called the Maunder Minimum, after the astronomer who discovered it. The cause remains a mystery, though some astronomers have theorized that it's normal for stars to occasionally go through such long, dormant periods. At the solar maximum, the Sun's magnetic poles actually flip. Like Earth, the Sun has north and south magnetic poles, around the solar minimum anyway. They get increasingly complex throughout the cycle until … at the height of solar activity every 11 years or so, they flip. So, sunspot activity is actually part of a 22-ish year cycle, in which the sun's poles flip and then revert, called the Hale Cycle. All of this is a subject of interest, not just because sunspots are cool, literally, but also because of sunspots' potentially disruptive effects on power grids and radio-based communications here on Earth. And we're going to get into that, but first we're going to get into a quick break for a word from our sponsor. Okay, sunspots are connected with other solar events like flares and coronal mass ejections, or CMEs. A solar flare is a sudden release of energy from the sun, and CMEs actually shoot hot plasma from the sun into space. We don't know exactly what triggers them, but the bigger the group of sunspots that appears, the more intense such solar weather tends to be. Flares and CMEs can send enormous amounts of energy and charged particles hurtling into collision with Earth's atmosphere. Here, they can cause magnetic storms that create beautiful auroras, but also disrupt or alter radio and cell phone communication. and can wreak havoc with satellite electronics and Earth-bound electrical grids. For example, during the solar maximum of 1989, a power surge triggered by solar energy damaged transformers that were part of the Hydro-Quebec power system. That surge left 6 million people in Canada and the northeastern U.S. without electricity for more than nine hours. The increase in radiation that accompanies a solar flare is a theoretical health hazard to spacewalking astronauts, So, researchers monitor solar activity and can call for delays of work outside of spacecraft until the danger is passed. Some people have theorized that there's also a link between solar weather and changes in Earth's climate, perhaps instead of climate change being driven by human industry and agriculture. It is true that our climate is influenced by a lot of complex factors, but research has shown that the solar cycle's effect is marginal compared with human influence, like the emission of greenhouse gases. Oddly, sunspot activity can actually help ham radio reception, because the increased radiation causes the atmosphere to bend higher radio frequencies back toward Earth. The ways in which solar weather can affect us here on Earth deserves its own episode, or episodes, and that's all on my list, but... Long before people were worried about power grids, radio transmissions, and global warming, they were watching sunspots. Ancient Chinese and Greek astronomers recorded their observations of sunspots over 2,000 years ago. A thousand years ago, records from Korea mapped sunspots, too. And a myth out of central Mexico tells of a sun god with a pockmarked face, perhaps implying sunspot observations. However... While other peoples continued their records over the centuries, there was a bit of a gap in Europe. For a long time, just about everyone there accepted the Greek philosopher Aristotle's idea that the heavens were perfect and unchanging. This included the Catholic Church, which considered heavenly bodies to be extensions of divine perfection. So, for example, when a large sunspot appeared for eight days in 807 CE, they dismissed the phenomenon as the passage of the planet Mercury across the sun. In 1611, descriptions of sunspots started showing up in European literature again, from Galileo Galilei and three other astronomers spread across the continent, thanks to the development of telescopes in 1608. Back then, people would rely on Earth's atmospheric conditions, like a decent fog or a cloudy haze, especially around sunrise or sunset, to observe the sun directly. And astronomers used a pinhole projection technique, just like we might today, to restrict the light hitting a mirror or a telescope, and then study the projection. One of those astronomers of 1611, a Jesuit priest by the name of Christoph Scheiner, tried to come up with an explanation that didn't contradict the church's teachings. So he argued that the spots were undiscovered planets that orbited very close to the sun. Galileo correctly figured out that sunspots were part of the sun itself, perhaps clouds, he thought, by closely studying their movement as they neared the edge of the sun's visible surface. By the mid-1700s, European astronomers were recording and compiling their observations of sunspots on a daily basis. As scientists accumulated more and more data, they began to notice that sunspot activity ebbed and flowed in a pattern. In 1843, astronomer S.H. Schwab was the first to describe the 11-year sunspot cycle. Since then, researchers have used an array of tools to learn more. including giant solar telescopes that were specially cooled to observe the sun's light without being distorted by its heat. In 1908, astronomer George Ellery Hale discovered sunspots' magnetic nature and used that discovery to prove the existence of a large magnetic field in the sun's interior. That aforementioned 22-year Hale cycle is named after him. More recently, astronomers have discovered star spots, that is, sunspots on other stars. Hundreds of other stars' spots have been recorded. One giant star in the constellation Triangulum bore a spot 10,000 times larger than the biggest spots ever observed on our sun. Researchers think that some younger stars might be so covered in star spots that they affect the stars' overall temperature. which means that our prior assumptions about those stars' sizes could be wrong. As of this recording, in fall of 2026, we're in the middle of the 25th solar cycle since researchers started tracking them. It started with a solar minimum in 2019, and the peak of the cycle is already past us. It started in 2024 and was accompanied by unusually widespread auroras. Activity will continue decreasing through the anticipated end of the cycle in 2030. But that doesn't mean we won't necessarily see some spectacular sunspots in the near future. You can follow along with solar changes at sites like spaceweather.gov, which is the space weather prediction center of the National Oceanic and Atmospheric Administration. They share daily data. including images of the solar weather, warnings for when it might affect us, and forecasts for aurora here on Earth. Today's episode is based on the article How Sunspots Work on HowStuffWorks.com, written by Patrick J. Kiger. BrainStuff is a production of iHeart Podcasts in partnership with HowStuffWorks.com and is produced by Tyler Klang. For more shows from iHeart Podcasts, visit the iHeartRadio app. Apple Podcasts, or wherever you listen to your favorite shows.
Speaker 1: Welcome to BrainStuff, a production of iHeartRadio. Hey, BrainStuff. Lauren Vogelbaum here. Sunspots. The ancient Chinese referred to them as stars inside the solar orb. One Renaissance astronomer argued that they were actually undiscovered planets. Today, some believe their appearance is linked to waves of UFO sightings and paranormal activity. The rest of us wonder if they're the reason for our dropped calls or spotty radio or internet service. Sunspots are the peculiar dark spots that pop up regularly on the surface of the sun. They usually appear in pairs or in groups called belts on either side of the sun's equator, between about 40 degrees and 50 degrees latitude both north and south. Sunspots vary tremendously in size, ranging from Less than 200 miles across, that's 30 kilometers, to many times larger than Earth. Small sunspots may last for less than an hour, but larger ones can last up to six months. Some are big enough to be seen by the naked eye. Keep in mind, of course, that staring directly at the unfiltered sun is an extremely bad idea because it can permanently harm your eyes. Side note here, yes, seriously. You can observe the sun and its spots safely by using solar viewing glasses or eclipse glasses. Or if you have a telescope or binoculars, you can fit them with a specialized solar filter meant for observation. Or if you don't have any of those on hand, you can always use a pinhole projector. Punch a hole in a stiff piece of paper and with the sun at your back, project an image of it onto another surface like a wall or another piece of paper. Do not mess around with the sun. it will win. Anyway, sunspots appear dark to us when viewed safely because they're cooler in temperature than the surrounding areas on the sun's visible surface. This is called the photosphere, and it has a temperature of about 10,000 degrees Fahrenheit, or around 5,500 Celsius. The dark interior of a sunspot can be about 40% cooler than the rest of the sun's surface. Sunspots are cooler because they're areas of intense magnetism, so intense that it inhibits the flow of hot material from the sun's interior to its surface. Sunspots occur because the sun isn't a hunk of rock like Earth, but a ball of continually circulating plasma, that is, hot electrically charged gases, that doesn't move in one piece. The interior and exterior of the sun rotate separately. And the exterior rotates more quickly at the equator than at the north and south poles. A point on the equator will only take 25 Earth days to go around, while a point near one of the poles could take 36. Over time, all of that messy and uneven movement twists and distorts the sun's main magnetic field in the same way that your bedsheets get wrinkled and bunched up when you toss and turn in your sleep. The bunched-up spots, the twists in the magnetic field lines, have so much magnetic power that they push on the circulating plasma beneath them and prevent its heat from rising directly to the surface. In other words, they become sunspots. The cooler sunspots appear darker, and the plasma blocked by them will flow into the areas surrounding them, making those even hotter and brighter than normal, thus making the sunspots stand out even more. I should say here that sunspots are still objectively very bright, about as bright as the full moon. The average sunspot is about as big as our planet, but the biggest on record, which appeared in 1947, was about 18 times as large as the whole surface area of the Earth. Due to the size of the sun, despite the slow speed of its surface rotation, a sunspot will appear to move across its surface about four times faster than a point on Earth would appear to move from space. In London, the Royal Observatory Greenwich has kept detailed records of the size and location of sunspots since 1874. Roughly every 11 years, the number of sunspots increases from nearly zero to more than 100, then decreases to near zero again as a new cycle starts. This pattern is called the sunspot cycle. Since the 1700s, sunspot cycles have varied in length between 9 and 14 years. At the beginning of the cycle, sunspots form in the sun's mid-latitudes, but as the cycle progresses, they occur closer to the equator. We think the cycle occurs because the sun contains a sort of conveyor belt that circulates plasma between the sun's equator and its poles and then back again over a period of years. The idea is that when sunspots that formed early in a sunspot cycle begin to decay and They leave a kind of magnetic imprint on the moving plasma beneath them. The conveyor belt carries that plasma with those magnetic imprints towards the poles and then back inside the sun. The magnetic fields within the sun are then distorted and intensified even more before the conveyor belt sends the plasma to resurface nearer the equator. There, the plasma forms new, even more powerful sunspots. During any given sunspot cycle, activity usually rises quickly and then declines gradually. The point where sunspots reach their peak of intensity is called the solar maximum, and the low point the solar minimum. Solar minimums usually last for several years, but they sometimes go on for much longer. For example, there was a 60-year period between 1650 and 1710 when there was little or no sunspot activity at all. This is called the Maunder Minimum, after the astronomer who discovered it. The cause remains a mystery, though some astronomers have theorized that it's normal for stars to occasionally go through such long, dormant periods. At the solar maximum, the Sun's magnetic poles actually flip. Like Earth, the Sun has north and south magnetic poles, around the solar minimum anyway. They get increasingly complex throughout the cycle until … at the height of solar activity every 11 years or so, they flip. So, sunspot activity is actually part of a 22-ish year cycle, in which the sun's poles flip and then revert, called the Hale Cycle. All of this is a subject of interest, not just because sunspots are cool, literally, but also because of sunspots' potentially disruptive effects on power grids and radio-based communications here on Earth. And we're going to get into that, but first we're going to get into a quick break for a word from our sponsor. Okay, sunspots are connected with other solar events like flares and coronal mass ejections, or CMEs. A solar flare is a sudden release of energy from the sun, and CMEs actually shoot hot plasma from the sun into space. We don't know exactly what triggers them, but the bigger the group of sunspots that appears, the more intense such solar weather tends to be. Flares and CMEs can send enormous amounts of energy and charged particles hurtling into collision with Earth's atmosphere. Here, they can cause magnetic storms that create beautiful auroras, but also disrupt or alter radio and cell phone communication. and can wreak havoc with satellite electronics and Earth-bound electrical grids. For example, during the solar maximum of 1989, a power surge triggered by solar energy damaged transformers that were part of the Hydro-Quebec power system. That surge left 6 million people in Canada and the northeastern U.S. without electricity for more than nine hours. The increase in radiation that accompanies a solar flare is a theoretical health hazard to spacewalking astronauts, So, researchers monitor solar activity and can call for delays of work outside of spacecraft until the danger is passed. Some people have theorized that there's also a link between solar weather and changes in Earth's climate, perhaps instead of climate change being driven by human industry and agriculture. It is true that our climate is influenced by a lot of complex factors, but research has shown that the solar cycle's effect is marginal compared with human influence, like the emission of greenhouse gases. Oddly, sunspot activity can actually help ham radio reception, because the increased radiation causes the atmosphere to bend higher radio frequencies back toward Earth. The ways in which solar weather can affect us here on Earth deserves its own episode, or episodes, and that's all on my list, but... Long before people were worried about power grids, radio transmissions, and global warming, they were watching sunspots. Ancient Chinese and Greek astronomers recorded their observations of sunspots over 2,000 years ago. A thousand years ago, records from Korea mapped sunspots, too. And a myth out of central Mexico tells of a sun god with a pockmarked face, perhaps implying sunspot observations. However... While other peoples continued their records over the centuries, there was a bit of a gap in Europe. For a long time, just about everyone there accepted the Greek philosopher Aristotle's idea that the heavens were perfect and unchanging. This included the Catholic Church, which considered heavenly bodies to be extensions of divine perfection. So, for example, when a large sunspot appeared for eight days in 807 CE, they dismissed the phenomenon as the passage of the planet Mercury across the sun. In 1611, descriptions of sunspots started showing up in European literature again, from Galileo Galilei and three other astronomers spread across the continent, thanks to the development of telescopes in 1608. Back then, people would rely on Earth's atmospheric conditions, like a decent fog or a cloudy haze, especially around sunrise or sunset, to observe the sun directly. And astronomers used a pinhole projection technique, just like we might today, to restrict the light hitting a mirror or a telescope, and then study the projection. One of those astronomers of 1611, a Jesuit priest by the name of Christoph Scheiner, tried to come up with an explanation that didn't contradict the church's teachings. So he argued that the spots were undiscovered planets that orbited very close to the sun. Galileo correctly figured out that sunspots were part of the sun itself, perhaps clouds, he thought, by closely studying their movement as they neared the edge of the sun's visible surface. By the mid-1700s, European astronomers were recording and compiling their observations of sunspots on a daily basis. As scientists accumulated more and more data, they began to notice that sunspot activity ebbed and flowed in a pattern. In 1843, astronomer S.H. Schwab was the first to describe the 11-year sunspot cycle. Since then, researchers have used an array of tools to learn more. including giant solar telescopes that were specially cooled to observe the sun's light without being distorted by its heat. In 1908, astronomer George Ellery Hale discovered sunspots' magnetic nature and used that discovery to prove the existence of a large magnetic field in the sun's interior. That aforementioned 22-year Hale cycle is named after him. More recently, astronomers have discovered star spots, that is, sunspots on other stars. Hundreds of other stars' spots have been recorded. One giant star in the constellation Triangulum bore a spot 10,000 times larger than the biggest spots ever observed on our sun. Researchers think that some younger stars might be so covered in star spots that they affect the stars' overall temperature. which means that our prior assumptions about those stars' sizes could be wrong. As of this recording, in fall of 2026, we're in the middle of the 25th solar cycle since researchers started tracking them. It started with a solar minimum in 2019, and the peak of the cycle is already past us. It started in 2024 and was accompanied by unusually widespread auroras. Activity will continue decreasing through the anticipated end of the cycle in 2030. But that doesn't mean we won't necessarily see some spectacular sunspots in the near future. You can follow along with solar changes at sites like spaceweather.gov, which is the space weather prediction center of the National Oceanic and Atmospheric Administration. They share daily data. including images of the solar weather, warnings for when it might affect us, and forecasts for aurora here on Earth. Today's episode is based on the article How Sunspots Work on HowStuffWorks.com, written by Patrick J. Kiger. BrainStuff is a production of iHeart Podcasts in partnership with HowStuffWorks.com and is produced by Tyler Klang. For more shows from iHeart Podcasts, visit the iHeartRadio app. Apple Podcasts, or wherever you listen to your favorite shows.
