Sun Series: You (Yes, You!) Can Help NASA Study the Sun
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Hey, Space Nerds. Here's another fun way that you can get involved with the total solar eclipse. So our friends at Third Rock Radio are giving you the power to choose the eclipse soundtrack with solar songs. Three days of music to get you in the mood for the eclipse. Each day has a different theme and things kick off on April 5th with songs all about the sun.

You can find more at thirdrockradio.net. Just look for the tab that says Solar Songs in the upper left. That's where you can submit your request and you can hear each day of Solar Songs from noon to 2 p.m. Central Time. All you have to do is pick the songs and Third Rock will play them back in honor of the total solar eclipse on April 8th. And hey, let them know Curious Universe sent you.

This is NASA's Curious Universe. Our universe is a wild and wonderful place. I'm your host for today, Jacob Penner. And in this podcast, NASA is your tour guide. You're listening to the third episode of our Sun series. From here on Earth, our neighborhood star can seem steady and predictable. But when you look at the Sun close up, there is a lot going on.

So, in the sun's honor, we're taking a deep five-part dive into the plasma. So far, we've covered how the sun and earth formed and influence each other and the surreal experience of a total solar eclipse. For this episode, I'm joined again by our producer, Christian Elliott. Christian, what do you have planned for us this time? Hey, Jacob. Well, to start, I want to tell you a little story.

I recently talked to this guy Chandresh Khedambadi. He's a chemical engineer and the story starts with him moving to Canada from India for a job. One that involves long nights driving around, taking measurements of oil wells in the icy north. So on one such night we were driving and obviously being February, I think it was around minus 20, minus 25 that time in Calgary. He was in this convoy following another truck.

Then, his colleague in the truck up ahead did something unexpected. So my operator pulled the truck over. He just stopped in the middle of the road. We were in a remote location in one of these backcountry roads. First, he thought the other truck had hit a deer in the dark.

And he came on the radio and he asked me to get out of my truck and look skywards. And sure enough, I did get out and look at the sky. And once the truck lights turned off, it took a little bit of a while to register what I was actually looking at. It was the northern lights. Chandresh had seen the aurora in documentaries growing up, but experiencing it firsthand was different.

The night pretty much started with a bit of a diffused glow. It's kind of just a dim glow which just sits there and doesn't seem like it's doing anything much. And then, boom, right away, it just lit up the entire sky. And we sat there and watched it for about 10, 15 minutes.

Once it was over, he drove home into the sunrise and tried to move on. But it felt like something had changed. It stayed with me for a couple of days. Like even when I was logging that well, you would think about the shapes and why it would dance in a particular way. He found himself imagining what Canada's First Nations people would have thought, looking up at the same sky hundreds and thousands of years ago.

He started researching how the sun causes the aurora and going out every night trying to see it again. He got into astrophotography, taking pictures of the night sky. You want a bigger and better show every time, right? It's almost like a high and you want the next high.

I've driven as far as three and a half hours almost towards the US border sometimes when you know that the data is good. Any night where you have to give up chasing the Aurora because you ran out of memory cards and you ran out of batteries and spare batteries, I think is a great night.

Experiencing the Sun firsthand changed Chandrash's life. Now he spends every night he can out in fields and on frozen lakes, chasing the aurora and even contributing data to NASA research projects. And he's not the only one. In this episode, I'm going to bring you three stories of people who took the Sun for granted for a long time, then were snapped out of it and fell off the deep end into Sun obsession.

When you start really paying attention to the Sun, you just see the world differently. Okay, I'm excited! So Christian, where do we start? So we've talked a lot already about this big year for our Sun, with eclipses, really high solar activity, and Parker Solar Probe making its closest approach to the Sun. Yeah, I think the official NASA name for it is the Heliophysics Big Year.

Well, I hadn't really thought about this before, but do you know where the term "big year" actually comes from? NASA didn't just come up with it out of nowhere.

Do you want me to tell you the real story? We kind of borrowed an idea from the birding community where people challenge themselves to have a big year where they see as many species of a bird as possible. And so we thought that we had an opportunity to have a heliophysics big year. That's Liz McDonald. She's a sun scientist at NASA, and she leads citizen science for heliophysics.

We've done stories about citizen science. That's like where people volunteer to help out with research, right? Yeah, exactly. That concept is at the very core of this big year. Here, Liz can explain it better than I can.

Citizen science is a way in which ordinary people can contribute to the scientific process and to various topics that NASA studies, from the moon to different planets to the aurora to the eclipses that are happening this year. And people can make discoveries.

When they're working on ambitious research projects, scientists pretty often run into one of two problems. Either there's just too much data for them to go through, or they just don't have the time or resources to collect the data all over the world that they need to answer their questions. And that's where citizens, these volunteer scientists, come in.

It's really expensive to build satellites and space is really large. So we are kind of data starved, but people are everywhere and people are always looking and finding unusual things in the data. And as a bonus, volunteering as a citizen scientist often overlaps with people's hobbies, like looking up at the night sky through a telescope or taking photos or just going for walks in the woods.

Wherever scientists look, they tend to find ordinary, curious people already collecting the data they need. Like photographs of aurorae, for example. They just don't know it yet. And one of the things I love the most about citizen science is the way that we really get to answer people's questions. And they ask really good questions, including some things that scientists might have overlooked.

And there are so, so many really fascinating projects going on during this heliophysics big year. Well, I'm excited to hear about them. So, Christian, you said you picked out three of them for me, right? So, what is stop number one? Well, how about I let Liz pick?

There's actually almost 20 projects that are part of the Helio Big Year. I just signed up for one of the projects earlier today because I realized how easy it was to sign up. That was the Eclipse Soundscapes project, which is about tracking how animals respond during solar eclipses. Ooh, soundscapes. Okay, I mean, that sounds right up our alley. Yeah, I was really excited about it too. So to learn more, I got in touch with the project's leaders.

Hello, my name is Dr. Henry Winter, but everybody calls me Trey, and I am the co-lead and chief scientist of the NASA-sponsored Eclipse Soundscapes project. The story starts a few years ago in a library in New York. Trey, a solar astrophysicist, was trying to describe an eclipse to someone who was blind, and he couldn't. He realized he kept describing the way the light changed, the colors, that sort of thing.

How do you describe a visual phenomenon to someone who's never seen? He floundered for a few minutes, and then he remembered a story his friend had told him. They were standing out in the field in the middle of nowhere, and there was no sounds around. And then as soon as the moon completely covered the photosphere, the bright part of the sun,

Day kind of turned into twilight around them. All of a sudden, the field erupted in a sound of crickets. He said it was like somebody had flipped on a cricket switch. It was so sudden. It was so immediate. And that got him thinking. We always talk about seeing an eclipse, but an eclipse is really an experience, right?

Yeah, the way that Kelly described this in episode two of this series really stuck with me. I mean, she talked about the way the temperature shifts and the way that the sounds change. Yeah, it's really a multi-sensory experience. And so Trey started on this quest to make eclipses more accessible. He made an app that could guide blind and low vision people through the 2017 eclipse in audio and with tactile feedback. Eclipse Soundscapes. Eclipse Soundscapes.

And then he thought, wait a minute, what about that cricket story? Was that really true? So he decided to create a citizen science project to study how animals behave during eclipses. A multi-sensory, accessible project that anyone could contribute to. Little did I know that there was a study done over 90 years ago by a person named Wheeler who actually looked into how eclipses impact wildlife.

So, is he saying that another scientist had this exact same question almost a century ago? Yeah. So, the guy's name is William Morton Wheeler. He's this entomologist with a big caterpillar-like mustache. And he'd found reports of birds ceasing singing during an eclipse in 1544. So, he teamed up with some colleagues who were experts on birds and mammals to do this study.

And the craziest thing is that that experiment happened in Boston, just a few blocks down the road from Trey's office. It actually took place around the August 31st, 1932 total solar eclipse that passed over the New England area in the northeast part of the United States. That's Mary Kay Severino, co-lead on the project.

So, it's the 1930s. This was well before NASA, of course, before the internet, before citizen science programs existed. And so what Wheeler did is he put out a newspaper ad.

And he received almost 500 responses. And those experiences weren't just what was the change in light levels and stuff like that, but they also reported what they heard, right, as well as what they felt. They felt temperature drops. Some heard crickets. Some heard a moment of silence. In particular, there's a lot of anecdotal observations from that old study about what animals do during eclipses.

Cows turn around and start to head back to the barn. I guess it's nighttime, it's time for me to go to bed. Bees, who are used to being out and about, all of a sudden realize, "Oh my gosh, I should be back in the hive. I better hurry up and get back there." So they zoom back.

My personal anecdote was for the 2017 eclipse, the team had found a place in the middle of nowhere that was a bird sanctuary. And the eclipse happened and we were all standing there in a sense of awe. Then out of nowhere, I heard owls start to hoot.

These animals are experiencing almost like a sped up version of dusk, night, and dawn that typically happens over several hours in just a few minutes. And so that creates some confusion in the natural world. But it's 2024, not 1932. So the team is working with some more advanced tech to study that confusion. They're using something called an audio moth.

Huh. And what is an audio moth? So this audio recorder can record a wide range of frequencies. Yeah, so it's this little handheld device. It's got these little bumps on it so that low vision citizen scientists can use it. You switch it on and you attach it to a tree or a park bench or something to listen for changes in the soundscape. The research team gave these out to a bunch of libraries, national parks, and volunteers ahead of the April eclipse.

The idea is that habitats are unique, so if you really want to learn something about how environments change during totality, you can't just ask people in Boston. The team's hoping to record 300 habitats all across the U.S. on April 8th.

And they actually got a trial run in too, during the Ring of Fire Annular Eclipse last fall. So there's actually people who have experience using these things, so what do you know about what it's like to use an audio moth to contribute to the project? Yeah, I got a hold of one group that tried out the audio moths last year and that are planning to participate again in April.

Hi, my name is Mary Perel-Moyt. I'm the Assistant State Coordinator for the Texas Master Naturalist Program. Mary got connected with NASA's Eclipse Soundscapes project through another Texas Master Naturalist, Chell Lindgren. His day job is NASA astronaut. The group participates in a lot of Earth-focused citizen science projects.

Last fall, volunteers gathered on a nature reserve on the south Texas coast with their audio moths for the annular eclipse. We preset these audio moths and put them out into different corners across the property amongst the mosquitoes and the thornbrush scrub and the south Texas sand plains.

The change in how the day felt around you was so tangible, not only in that temperature drop, but the whole world felt like it was going to sleep for just a little bit. The birds and the insects quieted and settled, and so did the 400 naturalists. They settled for a little bit too. Even with your eyes closed and your head pointed down, it was obvious that there was something happening.

It was magical. And we often think of eclipses as something you go to see. Where are you going to watch the eclipse? We often get bogged down in what will I do if it's cloudy because we are so focused on watching the eclipse. But they're multi-sensory experiences.

That's so cool, and it makes a lot of sense. Christian, what else do you have for us? Well, there are a ton more eclipse-focused projects that involve everything from using ham radio to bounce waves off the ionosphere to sending weather balloons up into the path of totality.

But I want to move past those and focus on a couple of projects that you can participate in anytime. Okay, sounds useful. I mean, evergreen projects, you know, join it when you're ready, right? Yeah, exactly. So remember Liz? She actually has her own citizen science project that's been going on for a number of years. Chandresh from the beginning of this episode is part of it. It's called Aurorasaurus. Huh.

Now, Christian, I've always been a T-Rex fan, but I'm sure that Aurorasaurus is a totally fine dinosaur too. Jacob, I'm so sorry to say that Aurorasaurus has nothing to do with dinosaurs, but I promise you this is going to be equally cool.

So, we talked a bit about the aurora in the first episode of our Sun series, but I think it's worth getting into what the northern and southern lights are in a bit more detail here. The aurora is kind of the last step in a process. It has many steps and starts on the Sun. Okay, Jacob, what do you remember about that process?

Oh, I did not sign up for a pop quiz. Okay. I know that the sun is sending out the solar wind in all directions all the time. It's this stream of charged particles. And they bump into Earth's magnetic field, which is this big magnetic bubble that's generated by our iron core. And it extends out into space to protect us. Yes. You aced it. So it's always being...

bombarded by pretty high energy particles. Those particles from the solar wind can get caught up in the Earth's magnetic field and they get transported from the sort of sunward side where they enter to the night side, basically the dark side of the Earth. And that energy gets actually stored up in the Earth's magnetic field, causes it to stretch a little bit like a rubber band.

Yeah, and since these are charged particles, which means they have electrical charge, they get stuck on the magnetic field lines and they have to follow them back down toward the poles at high speeds when that rubber band snaps back.

And since they've been accelerated, they actually are going to hit some of the particles in the upper atmosphere. And when they do that, they make a little bit of light. And that light happens really high up. So the colors that you see are mostly from the impact on oxygen particles up there and also a little bit from nitrogen.

So all those colors you see in the aurora, you're seeing Earth's magnetic field lines light up like the magnetosphere is in action and showing us how it's protecting us. Yeah, that's exactly right. And up near the poles, that pattern of energy storage and release is happening all the time. It's just a normal process for our planet. We do understand about like 90% of the physics of all of this process.

But since we're near solar maximum, when the sun is at its most active, we're seeing these bigger eruptions, these big flares on the sun. And they're sort of supercharging the aurora. And what that means for us is more dramatic displays and displays further south than usual. And these big events are things we just don't understand as well. But when that happens...

it disturbs the system like significantly. And so we really need more eyes on the ground and in space to understand what happens.

So basically you need photos of the aurora from the ground to match up with data from satellites passing overhead at the same time. But scientists like Liz are not photographers. They're not spending all their time out in the mountains of Canada or Scandinavia waiting for the aurora. Luckily for them, there are folks who do that. Scientists like Liz are super dedicated to studying the aurora using imagery, but there's this whole world of folks who are maybe even more dedicated.

Aurora Chasers. I've seen it hundreds of times. I'm very lucky. I've seen it from seven countries and still wanting more. Once you've seen it, it's really addictive. You want to see it again and you want to know why and how and all the rest. So it's just snowballed into me becoming an Aurora guide. Yeah.

That's Hanabella Nell. She's an Aurora Guide based in the southwestern UK and an ambassador for the AuroraSaurus project. Ugh, Aurora Guide sounds like an incredible job. Yeah, it definitely sounds fun. What she does is she takes people all over the world on these tours to see the Aurora.

It takes a lot of specialized knowledge to get people to the right places at the right times and to explain the science. But anyway, Hannah Bella started out photographing the Milky Way at night in dark sky areas of local national parks, kind of as a hobby. But then on a worldwide trip to dark sky reserves, she fell in love with the aurora in Alberta, Canada. I was supposed to go on to Bali in Japan, but something in Canada was calling me back.

She joined the Alberta Aurora Chasers, this group of thousands of dedicated chasers that have this active Facebook group where they share their photos by day and help each other chase down the aurora at night. It's quite like a family. It's really nice. It's really uplifting. Everybody's like, you caught that? That's amazing. It's like, oh, look what I got this time.

The way you or I might check the weather forecast, these folks check the space weather forecast. They're constantly looking for strong solar flares. They have the sun's 28-day rotational cycle on their calendars so they know when a coronal hole will rotate back toward the Earth. If it's facing Earth, it's go time. Charge your cameras. If the weather here locally is good, that is.

Well, I'm thinking of the eclipse chasers like Fred that we met in episode two of this series who are willing to go just anywhere to get a glimpse of an eclipse. And I'm getting similar vibes here. I mean, aurora chasers are also always running from bad weather and looking for clear skies, I imagine. Yeah, Hannah Bella signs off her emails with many thanks and clear skies, which I'm not

I might have to steal. But anyway, these chasers of solar phenomena, they're willing to drive hundreds of miles to be in the right place at the right time to experience a great show. And those shows can vary a lot.

When you think of the aurora, you probably think of green lines in the sky. That's what I saw the one time that I was lucky enough to experience it. But an aurora chaser can set you straight. It comes in so many shapes and varieties. It looks different every time. There's never two nights the same. You can have different colors. There's the red aurora, so you'll have green and then the red above it. Blue aurora, big blue pillars, absolutely stunning.

There's all this chaser lingo for Aurora features, like picket fences. And I can totally see how you get sucked in. There's always that promise of a bigger Aurora, a better Aurora, or just a different one that's always out there over the horizon.

Exactly, that's a big part of it. Do you remember how Chandresh started wondering about what indigenous people in Canada thought about the aurora? It's the same with Hanna-Bella. She loves all of this folklore about the aurora, which is different throughout the world. Each country does seem to have their own kind of amazing stories. Finland's got one about the fire fox. So the fox whips his tail in the snow, which then sparkles up into the sky, which is the aurora.

Never shake a handkerchief at the aurora or she'll come and get you. And you shouldn't wear your hair down otherwise you could get tangled up and taken to the sky. And while aurora chasers are out admiring the northern lights, they've also been known to make discoveries that scientists miss. One night stands out for Hanna Bella. It was sort of her entry into this world. She was at Pyramid Lake, an isolated spot deep in Jasper National Park in Canada.

all alone on this wooden bridge. I cycle out into the dark with my camera equipment and set it up. As soon as I've set it up, I see the aurora kind of building up behind the mountains in the north and suddenly it's getting taller and taller. There's suddenly these big blue pillars and then the aurora's horizon to horizon and rippling all above you like you're under the ocean. That's some absolutely magical kind of dancing around James Brown celebrating.

by yourself in the dark. But it was wonderful. And then, as the main show started to fade away, she noticed something unexpected. A sort of aurora she'd never seen before. The aurora's starting to bubble away in the north, but to the

There was a strange purple ribbon of light that looked a bit like a plain contrail going in the wrong place for aurora. But it just wasn't moving, it wasn't fading, and it looked like it was twisting. I was like, this is weird. I hadn't seen anything like this before. I hadn't really seen the aurora too many times at this point. So I turned my camera to start shooting in that direction, and it starts twirling a bit more. And then it starts developing these green, I call them picket fence lines.

lines coming off the edges of it. Wonderful. And I was like, oh my gosh, I'm capturing Steve. I'm sorry. Hang on. Did you say capturing Steve?

Yes, Steve was the name the Aurora Chaser group had given this mysterious pink line in the sky that they kept seeing. It's a reference to this movie Over the Hedge, where this mysterious hedge pops up out of nowhere and the woodland creatures name it Steve. And so this Steve is a big mysterious hedge in the sky.

Yeah, the Aurora Chasers are a funny bunch, but Liz had realized what a great resource they could be for her team at NASA. So, a few years back she'd launched Aurorasaurus, a way to connect scientists with the Chasers doing what is essentially this great science fieldwork. Liz had been seeing a lot of these sorts of photos of this phenomenon that Aurora Chasers were calling "Steve" popping up on the Facebook group. None of her colleagues knew what it was.

And so, when Hannah Bella uploaded her photos from the lake there, Liz reached out to her. And that was like my introduction to Aurorasaurus, and then from that point, the rest is history, let's say. Well, I'm on the edge of my seat here. Did Liz figure out Steve?

Well, by matching up photos from Hanna Bella and other chasers with satellite measurements, scientists figured out it's this rare sort of cousin to the normal aurora that forms super high up in the sky out of this trail of really fast moving particles.

They made an acronym for it so the chasers could keep calling it "STEVE." They'd gotten a little attached to that name. "STEVE" is a Strong Thermal Emission Velocity Enhancement, which refers to the particles that are causing that light. Oh, and funny enough, Liz realized these chasers had actually rediscovered "STEVE." Oh, what do you mean?

Well, after Liz had published the research about Steve, she found a paper from a century ago with these black and white photos of the same line up in the sky that look a lot like Hanna-Bella's. They'd been taken by some scientists in Norway who died a few years before the space age began, right before satellites opened up this new era in sun science and aurora physics. So this discovery had sort of been overlooked.

And they called them feeble, homogeneous arcs of great altitude. Which is true. They are a different altitude than the typical aurora. I'm getting a lot of resonance here with the Eclipse Soundscapes Project, citizen scientist,

answering these open questions that were forgotten from almost 100 years ago. Yeah, you're totally right. Citizen scientists really seem to have a knack for catching these things that scientists have missed and filling in the gaps. It's kind of this mutual rock star effect.

It's a really great partnership. Scientists are motivated by figuring out particle dynamics. Aurora chasers are motivated by just the sheer beauty of this natural phenomena. To Liz, the aurora is interesting. To aurora chasers, it's addicting, life-changing. Liz brings the expertise, and they bring the passion.

The science of it is constantly mind-blowing and it's been really inspiring to be able to work with people like these amazing NASA scientists and people who are studying it full-time. As somebody who is a citizen scientist, I never thought I'd have that opportunity and I've learned so much. And I will shout 'Aurora' from the rooftops because I think that other people will feel the same to get involved with science. Science is magic.

Now, there's one more project that's just so cool we have to talk about it. It's called Sun Grazer.

And to me, it's a story about how sometimes NASA's intrepid spacecraft can surprise even the engineers who build them, and how citizen scientists can surprise the scientists who use those spacecraft for research. The Sun Grazer story starts with a very special spacecraft called SOHO, which was designed to study solar eruptions on the sun's surface. SoHO is one of the...

oldest and, in my very unbiased opinion, one of the most amazing spacecraft missions that we've ever launched. I don't think you could find a solar physicist that would disagree that it's been probably the most influential heliophysics mission of all time. This is Carl Battams. He's a scientist at the Naval Research Lab, and he's the principal investigator on the Sun Grazer project, basically the lead scientist.

SOHO launched back in 1995 and it immediately started taking these super great photos of the Sun's surface. One ignition and lift off of SOHO and the Atlas vehicle on an international mission of solar physics. But since it was the 1990s,

scientists started uploading those photos to the internet, which was brand new, so that the public could see them. And pretty quickly, they realized SOHO had an unexpected superpower. And a small group of amateur astronomers started looking at the images and realized, hey, look at that. There's this tiny little dot moving. There's a comet in these images. Everyone's very excited and they make some measurements of these comets. But no one really appreciated just how many comets were going to start turning up.

So just to get this straight, this is a spacecraft that studies the Sun, but it's also catching glimpses of comets. Yes, this will be a comet story for a while, but I promise it's still a Sun story, if you bear with me for a minute. This comet discovering ability was just a totally unexpected trick that SOHO had up its sleeve.

SOHO is purely a sun-watching spacecraft. It is designed exclusively to study the surface of the Sun, solar eruptions and that kind of thing. So there's no intent for it to discover comets. It's just by luck and good design

SOHO is one of those spacecraft that has a coronagraph, a disc in front of its camera that perfectly blocks the sun's surface, just like the moon does during a total solar eclipse. And so it lets us see faint objects really close to the sun that it's usually way too bright to see, like comets. Anyway, pretty soon people were looking at the images and reporting new comets to NASA.

And Sungrazer was born.

Before SOHO came onto the scene, scientists had only discovered about a dozen of these sun-grazing comets. And now SOHO discovers one about every two days. So that was like 23 years ago now that website was launched and miraculously we're still going strong.

How many comets has SOHO discovered exactly? I'm thinking like hundreds or thousands even at this point? Well, as we were getting ready to publish this episode, the team actually just hit a huge milestone. 5,000 comets. Holy smokes, that's a lot of comets. Yeah, and this spacecraft is pushing 30. It was designed for a two-year mission studying the sun, but it just keeps on going and keeps on giving in this unexpected way. It

advancing comet science and sun science at the same time. Soho is overwhelmingly the most successful comet discoverer in history. I think right now we're approaching two-thirds of all officially documented comets carry Soho's name. Can we back up here for a second? Just for those of us who aren't comet experts like Carl here, what kinds of comets is Soho looking at?

Yeah, so if we go back in time, billions of years ago, before we had planets in our solar system and there was just this big spinning cloud of dust and ice, that material eventually formed our planets. But there were leftovers. Yeah, and what I've heard about comets is that they are those leftovers, right? They're basically these super cold mushed together balls of frozen gas and dust and ice and rock and all that stuff that just didn't make the cut to be a full planet.

But what I always pictured is that they were just way, way out there in like the far reaches of the solar system. Just kind of lurking out where we couldn't see them most of the time. Most comets are like that. They take these long trips through space and we only see them every once in a while. But a few have these really funky orbits that take them super close, really too close to the Sun.

"Sun Grazer" is focused on what we call "sun grazing comets" and the name is kind of a giveaway there. So "sun grazing" literally means these things graze the surface of the Sun really ridiculously close to the Sun. Most of these comets that SOHO has discovered belong to a single family. It's called the Kreutz Group. It's named after a German astronomer that first discovered these sun grazing comets.

Some thousands of years ago, a moderately big comet got a little bit too close to the Sun and it caused this big comet to literally fall apart and it crumbled into a whole bunch of smaller comets.

This one was a middle-of-the-road comet, about a few miles in diameter. If miles across is middle-of-the-road, then these things are a lot bigger than I realized. We've certainly seen much, much bigger comets than that. So it really doesn't take a very big object to create 5,000 house-sized comets.

Anyway, this crumbly pile of smaller comets continued in its parent comet's elliptical orbit way out into the solar system and back. It's kind of like a big oval racetrack with the Sun on one end. And eventually they get back to the Sun again.

Same process happens. They get too hot. They get too close to the sun. They fall apart again, disappear off into the solar system. And you do this a couple of times. And what you end up with is this massive population of tiny little comets that fly right by the sun and vaporize. So what I'm hearing is that every time this comet group comes by the sun, it falls apart a little bit more. How long has this been going on?

Undoubtedly, these tiny little sun-grazing comets have been vaporizing for thousands of years unknown to us. But prior to kind of the modern spacecraft era, the only ones that ever got reported were those that were bright enough that they could actually be seen in daylight skies.

Before Soho, the sun was just too blindingly bright for us to see what was going on. And by now, it's sort of the end stage for this Kreutz group.

It's falling apart into ever smaller pieces, and before long, it'll be gone. But the upside is, with every orbit, there are new comets to discover. At least briefly. We're sort of slowly witnessing the death of a large comet. Well, it's kind of nice and kind of poetic that people are willing to look at this SOHO imagery and do all this work to discover these comets, even though they won't last, right? Even though we're seeing their last gasps right before these comets go.

So Christian, let me bring it back to the science here because this is cool and it sounds like there's some cool space detective work going on. But like, why do it? I mean, what can we learn from these dying comets? Yeah, I wanted to know that too. And Carl was ready for that question.

Yes, we've got all the comet stuff because we've got 5,000 comets, blah, blah, blah, lots of comet science coming out of it. But what's also really awesome is that we are witnessing these things interacting with the near-sun environment. We're witnessing them interact with the solar wind, and the solar wind makes comet tails move and wiggle around.

By watching comet tails wiggle, we can measure the speed and direction of the solar wind. Kind of like a windsock at an airport.

We've even seen comet tails get hit by coronal mass ejections. And with the ones that pass really, really close to the Sun, like through the Sun's atmosphere, we can see how they interact with the magnetic fields there. The dust from those comet tails clings to those magnetic field lines, kind of like how the solar wind particles in the aurora follow Earth's magnetic field lines.

Both of these phenomena are sort of like messengers for us that reveal the sun's invisible behavior. Wow, that's pretty amazing. Yeah, and that's not all. To close, I want to tell you about one dedicated Sun Grazer contributor.

This isn't an easy project to work on. You aren't going out and gazing at the aurora or at eclipses. It's really hard work searching through these images for tiny, faint objects for hours and hours. "Sun Grazer" is a very challenging project. I wouldn't want to give anyone the impression that it's something that you could just kind of casually sit down and glance at for 10 minutes while you're eating your lunch.

But still, if you aren't careful, the sun can suck you in.

That's Hanjie Tan. He joined Sungrazer in 2009 as a middle schooler in China. He found his first comet right away, looking through the Soho imagery. The comet C-2009Y55.

I discovered it a month after I joined the Sun Grazer project when I was just 13. And that discovery was starting my interest in physics and astronomy. Sun Grazer got him thinking about space and wondering if there could be life elsewhere in the universe. Really set him on his trajectory toward becoming an astronomer and studying asteroids.

Since middle school, he's discovered 200 sun-grazing comets through 10,000 hours of searching. And he's actually the guy who discovered the 5,000th comet just last week. Wow, what a cool milestone. Yeah, he has poured so much time into this that he really deserves this success. Anyway, whenever new photos from Soho come out, he dives into them.

You look at a few images in a row and you can start to see movement and identify the comets. Yeah, I can see how that would add up and take a lot of time and dedication. No kidding. And it doesn't stop there. He actually built an AI program that goes back through all of the SOHO imagery to look for comets that other contributors missed. And that's how he found his favorite SOFAR. It's called SOHO-4464.

had a weird orbit and it was very dim. So it had been missed for years. My earliest comet discovered in the archives data back to image from 1997. I found this comet years later, even though the picture was captured when I was just a kid learning to speak. They had been missed for over two decades before I identified them from the vast ocean of stars.

His next goal is to discover a comet on his own, using his telescope. And he almost did last year. Soho project teach me, like, don't give up, just keep going. The next comet is waiting for you.

Wow. Well, this has been a wild ride. Christian, thank you so much. Thank you, Jacob. And remember, whether it's eclipses, aurorae, comets, there are so many citizen science rabbit holes you can fall down into. All you have to do is keep your eyes open and your ears and all your other senses to keep experiencing the sun. And of course, don't forget to stay curious. Thank you, Jacob. And until next time, I'm wishing you clear skies.

This is NASA's Curious Universe. This episode was written and produced by Christian Elliott. Our executive producer is Katie Konins. The Curious Universe team includes me, Jacob Penner, Mattie Olson, Michaela Sosby, and of course, Patti Boyd. Christopher Kim is our show artist. Our theme song was composed by Matt Russo and Andrew Santaguida of System Sounds.

Special thanks to the NASA Heliophysics team, Julia Tilton and Scott Swafford. If you want to get involved in Sun Grazer or Aurorasaurus, go to nasa.gov/eclipses

And if you catch this episode before the April 2024 total solar eclipse in North America, I'm sorry to say it's too late to get an audio moth. But there is still time to participate in eclipse soundscapes the old-fashioned way. You can write down your experience of the eclipse just like folks did in 1932. And you can help out by listening through and analyzing the data after the eclipse.

And if you plan to experience our star through an eclipse, please, please wear approved eclipse glasses before and after totality. If you enjoyed this episode of NASA's Curious Universe, please let us know by leaving us a review and sharing the show with a friend. And remember, you can follow NASA's Curious Universe in your favorite podcast app to get a notification each time we post a new episode. This is an official NASA podcast.

I'm sorry, hang on. Did you say capturing Steve? Yes. It's my dad's name, too. Special thanks to the real Steve. Earthly Steve. It's also my middle name. Wow. I mean, technically it's Steven, so it's, you know.

Really, really, Steve is my father. Actually, my name is Steve. Actually, everyone's name is Steve. I think we've got it. I don't have any other Steve comments.