How can the solar corona be hotter than the surface? What has the Parker Solar probe learned so far? What do magnetic fields have to do with all this? I discuss these questions and more in today’s Ask a Spaceman!
This episode is sponsored by BetterHelp. Give online therapy a try at betterhelp.com/spaceman and get on your way to being your best self. Visit BetterHelp to get 10% off your first month!
Support the show: http://www.patreon.com/pmsutter
All episodes: http://www.AskASpaceman.com
Follow on Twitter: http://www.twitter.com/PaulMattSutter
Read a book: http://www.pmsutter/book
Keep those questions about space, science, astronomy, astrophysics, physics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE!
Big thanks to my top Patreon supporters this month: Justin G, Chris L, Alberto M, Duncan M, Corey D, stargazer, Robert B, Naila, Sam R, John S, Joshua, Scott M, Rob H, Scott M, Louis M, John W, Alexis, Gilbert M, Rob W, Jules R, Mike G, Jim L, David S, Scott R, Heather, Mike S, Pete H, Steve S, wahtwahtbird, Lisa R, C, Kevin B, Michael B, Mark R, Alan B, Craig B, Mark F, Richard K, Stace J, Stephen J, Joe R, David P, Sean M, Tracy F, Sarah K, Ryan L, Ella F, Thomas K, James C, Syamkumar M, Homer V, Mark D, Bruce A, Bill E, Tim Z, Linda C, The Tired Jedi, Gary K, David W, dhr18, Lode D, Bob C, Red B, Herb G, Stephen A, James R, Robert O, Lynn D, Jeffrey C, Allen E, Michael S, Reinaldo A, Jessica M, Sheryl, David W, Sue T, Josephine K, Chris, Michael S, Erlend A, James D, Larry D, Matt K, Charles, Karl W, Den K, George B!
Hosted by Paul M. Sutter.
All Episodes | Support | iTunes | Spotify | YouTube
EPISODE TRANSCRIPTION (AUTO GENERATED)
On Wednesday, November 6, 2024, the Parker Solar Probe passed within 376 kilometers of the surface of Venus. The purpose of this close flyby was to accomplish a gravity assist maneuver, where the probe stole some of Venus's momentum for self so that it could change its orbit and bring itself even closer to the sun. The probe has already made several close passes of the sun, but the next will be its closest reaching just a touch above 6,000,000 kilometers from the solar surface. That's less than 9 times the radius of the sun. At the moment of closest approach, the Parker Solar Probe will be traveling at nearly 700,000 kilometers per hour, making it the fastest object ever designed by human hands.
To give you a sense of just how fast that is, the Parker Solar Probe gives us the rare opportunity to switch units. We actually can reasonably express its speed as a fraction of the speed of light. At its maximum speed, 700,000 kilometers per hour, that is 0.06%. C. We never get to do stuff that that less us say things like that.
That's amazing. And the mission the mission of the Parker Solar Probe is to investigate the mysteries of the sun's corona, which is its outer atmosphere. Specifically for decades, we've known that the visible surface of the sun, called the photosphere, has a temperature of around a few 1000 Kelvin, give or take. It's it's hot. But the corona itself, the outer atmosphere has a temperature in the 1,000,000 of Kelvin, which is, super hot.
And it's like switching on a light bulb, and the bulb itself is warm to the touch, but the air around it is a 1000 times hotter. What gives? Well, what gives? I'm going to tell you right away that the answer is magnetic fields. Now, if you've listened to this show for any length of time, you know that magnetic fields are the best, and they are one of my favorite things in all of physics.
If you've got a problem, magnetic fields can solve them. If you've got a mystery, make sure you check magnetic fields first. Magnetic fields play this underappreciated role in most scenarios when it comes to astrophysics. You know, magnetic fields are the cause of and solution to most of life's problems, but I know that recently I haven't had a lot of chances to bring in magnetic fields. And so by way of apology to one of my favorite aspects of the physical universe, we're pretty much going to devote an entire episode to honoring them.
But before magnetic fields hog the spotlight, let's take a step back and set up the problem in a little more detail. I'm sure you're familiar with the sun. It's that giant ball of fire in the sky. And the first thing that we need to note about the sun as we're about to plunge into the strange and wonderful physics that control various parts of it is that strictly speaking, it has no surface. I know.
I know. I just used the word surface only a few minutes ago, so I should probably clear this up. Look. The sun is a giant ball of fire in the sky or in more modern physics parlance, it's a self gravitating ball of plasma. And trust me, both balls of fire and self gravitating balls of plasma don't have solid surfaces.
There's nothing for you to stand on ever no matter how deep you go. Even if you were to somehow survive the crushing pressures and insane temperatures, it's all just goop all the way down. Now, the sun does have a visible surface. It's the sphere that we usually associate with that object called the the sun, and that is the photosphere. That is the point where the pressures and densities within the sun dropping up.
That light can finally escape. Below that depth, light gets trapped. It takes, like, a 1000000 years or something crazy to go from the core, to the visible edge. You know, it's just it's it's just so hot, so dense, so frenetic. Now photons just bounce around like crazy, but then they reach this edge, this precipice where the densities are low enough, the temperatures are low enough, and light can just blast out into space.
That's called the photosphere. That photosphere, that visible surface, like I said, has a temperature of few 1,000 Kelvin and there's a lot going on on that visible surface and something that's going to play a a big role later on is something called granules. So the the ball of the sun, the plasma in the sun, it's constantly churning. You know, it's not like the Earth or the moon or Mercury. It's not a solid ball of rock.
It is a goop of plasma where some goops of plasma are hot, and they buoy their buoyances, so they rise to the surface. They reach this photosphere, then they're able to release a lot of light in which cools them off and then they slink back down to the surface. And it is like a boiling pot of water, except the boils, these granules are the size of, you know, continents. They are thousands of kilometers across. One layer up from the photosphere is something called the chromosphere or sphere of color, which is a thin layer of plasma, the thing here being a few 1000 kilometers, that is dominated by the emission of red light from hydrogen atoms, but it's so much dimmer than the photosphere that we never get to see it except with specialized instruments.
And otherwise, the chromosphere will not be playing a role in our store. And above that, in this smooth transition, I I'm calling these things layers, but it really is a smooth transition from one region to another. The next smooth transition brings us to the corona, the sun's outermost layer. And for all intents and purposes, we call it the atmosphere of the sun. Normally, we only get to see this during the eclipse, hence, the word corona, crown.
It looks like it's crowning the moon which is pretty cool. Nowadays, we do have specialized instruments that block the light from the sun. We can look at the corona anytime we feel like it. The corona is huge. It's twice the radius of the main body of the sun and it's also incredibly thin.
It's over a 1000,000,000,000 times thinner than the Earth's atmosphere. And one of the curious results of that is that it's so thin that despite its insane temperatures, you wouldn't actually feel it. You could go swimming in this 1,000,000 Kelvin plasma, but it's so thin it's it's a harder vacuum than anything we can create in the laboratory. And so to actually feel temperature, you need things. You need molecules.
You need atoms actually hitting you and delivering their energy to you. That's how you feel temperature. But it's so thin, there's, like, you know, one atom, it, like, hits you, and then a little while later, you get hit again by one tiny little atom, and then again, and there there are all these awkward pauses in between it. And so you never actually get to feel that 1000000 Kelvin temperature, which is pretty wild. Like I said, between all these layers, there's no solid service.
There's no rigid boundary, there's just transitions from one kind of plasma to another. And that is what's going to help us understand the the mystery of the temperature of the corona is to realize that the corona isn't really separate from the sun, or the body of the sun. The way that our atmosphere, we can think of it as separate from the body of the Earth because air is very very different than rock. And, yes, they do interact, but largely, there's there's the air and then there's the rock. It's not so much with the sun.
If we're going to investigate the corona, we can't just look at the corona in isolation. We have to plunge deeper into the body of the sun. We have to go down into the photosphere and maybe even deeper to try to find the origins for the heat of the corona. But, it's it's not all crazy. It's not all hectic, you know, to this giant mishmash because we are generally able to separate the body of the sun which is everything in the photosphere and lower from the atmosphere which is starting with the chromosphere and extending out through the corona.
And we can separate these or we can at least attempt to understand the physics of these, by deciding who's in charge. You know, in physics, we care a lot about what forces govern the processes happening in a system. Because it's those forces that determine the overall look, shape, evolution, attitude, refined taste, and so on of that system. For example, if I throw something at you, then I say that the number one force that matters is gravity. Gravity is what sets the arc of that curve of the motion of that object as I throw it to you.
If I want to understand how far that ball is going to get, on where it's gonna land and how fast it's gonna be when it lands, I have to turn to gravity. Gravity is the number one force here on the surface of the Earth. Yes. There are other forces that play a role. Absolutely.
Like air resistance affects the motion of the object, but that air resistance plays second fiddle to gravity. I have to nail the gravity first and then I can add in more details later. In this case, on the surface of the earth, the gravitational force is the front man. It's the lead singer of the band of physics that determines what happens. And when it comes to the sun, in the body of the sun, the photosphere and lower, gravity is force number 1.
It controls and dominates everything else that happens, and indeed everything else that does happen is a result of the gravitational force like you go all the way down to the core and you've got those crazy nuclear reactions, the fusion of hydrogen into helium. What's powering that? Gravity. You have these tremendous granules, these continent sized blobs of plasma rising to the surface, cooling off, and slinking back down. What's driving that?
Gravity. Gravity is pulling them back down, and then gravity, it's it's in response to that gravity that there is this buoyant force that brings cells up to the top, that brings granules up to the visible surface, and then back down, gravity is in charge of the body of the sun. But in the atmosphere, starting with the chromosphere and working its way out through the corona, gravity isn't the lead singer anymore. In instead, there's a new number one and that's magnetic fields. Everything that happens in the atmosphere of the sun happens because of magnetic fields or in response to magnetic fields.
Their presence, their strength, their direction determines what happens in the atmosphere of the sun. If you're some random particle floating around in the body of the sun and you need something to do, you ask gravity. Gravity tells you what to do. Yes, there are other forces involved. There's like radiation and buoyancy and nuclear reactions, but all of those are happening in response to the presence of gravity.
If you're in the atmosphere, you don't ask gravity what to do anymore. Yes. There is the gravitational pull of the sun if I'm out there swimming through the corona. Of course, I feel the gravity of the sun, but gravity isn't in charge out there. What's in charge are the magnetic fields.
They determine the physics of the corona, not gravity. Because of this, we know that the heating of the corona has to involve magnetic fields because they're the lead singer. They're the thing that are driving the physics of the corona. It is magnetic fields and so if we're gonna heat up the corona, magnetic fields need to be involved. The rest of the band plays along.
Gravity still plays a role. There's other physics that play a role, but magnetic fields are the star in this region. If we're going to heat up the corona, it has to be because magnetic fields are doing something. Now what is that something? Now we know magnetic fields are in charge here, and we also know that there's this smooth transition from the interior of the sun to the corona.
There's no solid surface. There's no boundary. There's no, like, rigid thing. We call it the photosphere just because that's what emits the most light, but otherwise, it's a smooth transition. So we know whatever is heating the corona has to be connected to the depths of the sun, but has to be driven and controlled by the magnetic fields.
We know it can't be a normal heat transfer process. You know, normally, if I take a hot object a and cold object b, and I press them together and I wait a while, then their temperatures will will reach equilibrium and the heat will flow from object a to object b. That's like basic second law of thermodynamics stop, but we know that can't work because the thing providing the heat is the sun itself, but that object, the sun, the body of the sun, the gravity controlled body of the sun is at only at a few 1,000 Kelvin at its outermost layer. And that's much much much much colder than the corona itself. You can't put a cold thing up against the hot thing and have heat flow from the cold thing to the hot thing that violates the second law of thermodynamics.
So it can't just be a normal heat transfer process. It has to be something else. Some sort of interesting mechanism has to be at play to pull some energy out of the body of the sun, out of the gravity dominated body of the sun and transport it into the corona. But how much energy are we talking about? Ironically, not that much and that's because of the wonderful and surprising role that helium plays in all this.
Yes, helium. Welcome to the stage. You're not gonna be the lead singer today. You you Helium usually doesn't get any airplay at all, and it's no surprise why, because helium doesn't really, do much ever. But it makes up 25% of the mass of the sun, and because of that, it gets to it gets to be on the stage.
Not lead singer, but more like assistant drummer or something. Okay. You know, it's way in the back, but, you know, it's there. You know, it's got a tambourine or maybe a cowbell or a triangle and it's and it's doing its thing. Okay.
It's playing its role. And now, here, what the cool thing that helium does is that, the temperatures at the photosphere. You know, the outermost boundary of the main body of the sun, the last place where gravity plays the most important role, that region, the temperatures a few 1,000 Kelvin are cool enough that helium, which normally carries 2 electrons with it, only loses one of them. You know, if you if I take an element, or an atom, and it's got its nucleus and it's got electrons, if I heat it up, eventually, those electrons start to wander away. They get minds of their own.
They're not bound to the atom anymore, and they just go wandering off. So the more energy I give to atoms and molecules, the more they tend to lose their electrons. Now the temperatures here at the photosphere, the helium loses one of its electrons. That means it still has an electron hanging out, like attached to it. And this means that the helium can easily pump out a lot of radiation.
Because it can jiggle that electron to higher and lower levels and through that emit a lot of radiation. And because it can emit radiation, it can dump out a lot of heat. It can carry away energy, and that contributes to the overall general glowing of the sun. And it also keeps the temperature in check because there's an easy escape hatch for the sun's heat. If you're in the photosphere and, you know, there's like a big granule that comes up and it's got a lot of heat pulling up from the core, Well, you can put it towards the helium and the helium can glow really really easily and it can it can cool you off.
But once things heat up just a little bit, the helium loses its other electron and this makes it much much harder for it to release radiation which means it's better at trapping heat. In other words, the helium in the body of the sun is good at releasing heat while the helium in the corona is good at holding on to heat. Solar physicists call this transition between high helium that has lost one electron and helium that has lost both electrons. They call it evaporation because it kinda sorta looks like boiling water to give off steam with the steam holding on to a lot more heat than the water, but it's not a perfect analogy so we'll just leave them with that and move on. The upshot of all this is that you don't need that much energy to heat up the corona to insane temperatures.
Because once you put in a little bit of energy, then helium loses its electron, stops releasing heat, starts holding on to heat, acts like a big thick blanket, and then the heat just builds and builds and builds and builds on its own because there's nothing to release it. So the amount of energy you need to add to the corona to bring it to a temperature of a 1000000 Kelvin is something like 1 kilowatt for every square meter. One kilowatt, that's like that's the energy you need to run a dishwasher. So if you imagine and and it happens it just so happens a dishwasher is, you know, roughly, very roughly a square meter in area. So if you were to imagine hovering the surface of the sun in dishwashers, that's the amount of energy the sun needs to produce to heat up the corona to a 1000000 degrees.
I mean, that's that's not a small amount of energy, but it's only less than 1 40 thousandth of the total energy emitted by the sun. So that's the cool thing about the coronal heating problem is that you don't need a lot of energy to do the trick because helium plays this interesting role. It switches from being able to release heat easily to be trapping heat really easily. And so once you put a little bit of energy into into the corona, the helium switches states acts like a security blanket, and then the heat just ramps up and up and up and up. With just a small amount of energy relatively speaking, you know, enough to power dishwashers covering the surface of the sun, you can quickly shoot up to a 1000000 Kelvin like it's no big deal.
This is good. This means whatever we use to heat up the corona can be really really inefficient and will still do the trick. And magnetic fields, let's be honest, for as amazing as they are, are not the greatest at transferring energy from one place to another. So if magnetic fields are gonna do it, they don't have to do that great of a job, and the other feedback mechanisms are going to kick in to heat up the corona. And we know where the heating has to take place.
So we know it has to involve the whole sun. We know it has to involve some sort of interaction between the body and the atmosphere because there is no rigid surface. The photosphere talks to the chromosphere. The chromosphere talks to the corona. We they all connect together smoothly.
So we know we have to involve all the layers somehow. We know it has to involve magnetic fields. We know it doesn't take a lot of energy, and we know it has to happen. The heating has to take place somewhere between the photosphere and the corona. It can't start in the photosphere because the magnetic fields there aren't strong enough, And it can't start in the corona because the corona is is already hot.
As soon as you get to the corona at outside the chromosphere, as soon as you reach that, it's already a 1,000,000 kappa. It's not like this like slow ramp up thing. It's like, boom, you're there. So the heating has to take place in that narrow window between the photosphere and the corona. This region is appropriately known as the transition region and it's a layer sitting right on top of the chromosphere.
It's razor thin. We're talking only a few 100 kilometers across which is crazy to think about considering all the other scales we're dealing with. The granules in the photosphere themselves are the size of continents And now we're talking about a layer a few 100 kilometers across at most where all the action takes place. This is where it's happening. This is where the corona is getting its heat.
The transition region is perhaps the least understood part of the sun because there's no clear lead singer. The bottom of the transition region, gravity is the star of the show. It's the most important physical thing we have to care about. And at the top of the transition region, it's magnetic fields. In between, it's kind of both or neither depending on how you frame it.
There's no clear lead singer. It's hard for us to track and follow the physics at play because there isn't just one single set of equations that bosses everyone around, there's multiple ones. And I know I'm mixing metaphors here, but I'm on a roll, so please go to patreon.com/pmsutter if you would like better metaphors. That's patreon.com/pmsutter. I I truly appreciate all of your contributions.
So we know whatever is heating the corona, whatever trick of magnetism is making it all possible, it's happening here because as soon as you leave the transition region and enter the corona, it's already fully ramped up to a 1000000 Kelvin. So here's what we got. We have to connect the body of the sun to the corona. We have to give way from gravity dominance to magnetic field dominance. Magnetic fields have to be the one doing the work of heating up the corona, and they have to do it in this region that is a few 100 kilometers across and using a few dishwashers worth of energy to make it all happen.
And this is where the Parker Solar Probe comes in. To study this region of the sun, the probe comes packed with 4 suites of instruments named, and if you're searching for new baby names, grab a pencil. We've got fields, whisper, ISIS, and sweep. Yes, those are all acronyms, and no, I'm not going to spell it out. Fields is a bunch of magnetometers to measure magnetic fields.
ISIS, it measures high energy particles. Whisper is, it's a camera. And then sweep measures the solar wind. All of this is powered by solar panels, which is, a no brainer here for this spacecraft. And all these instruments together work to study the corona, the solar wind, that's the stream of particles emanating from the corona, and the transition region.
So, like, one instrument gives us a picture, a visible image, picture of of the plasma. Another one sees a pulse of energetic particles. Another one measures the change in magnetic fields and so on so that we can really get a comprehensive view of what's happening in this transition region and what's powering the heating of the corona. And those dynamics, the stuff happening in the plasma of this region of the sun in the transition region in the corona is all about waves. Waves are a likely culprit behind coronal heating because waves carry energy and momentum.
If you're standing on an ocean shore, you're seeing those waves rolling, they crash against the the shore. Those waves were sourced sometimes 100 of kilometers away. There were some energy input into the ocean like wind or a storm, and it generated the waves, and the waves moved through both space and time, and they carried that energy somewhere else. And then when they hit the shore and you hear the roar of the wave, you see the motion of the water molecules, you see how the sand responds. If you're standing there, you can be hit by the wave.
That is energy being delivered to you from a distant source. That is what waves do. They are messengers. They are couriers of energy and momentum. And there can be waves in water.
There can be waves in atmosphere. There can be waves in solid rock. And there can be waves in these high temperature plasmas. And waves and and waves are doing the thing that we need to do. We need to transport energy from the body of the sun, from the photosphere up through the transition region into the corona.
But the waves here in the transition region, in the corona, in the atmosphere of the sun, they're not just any waves. They're Are you ready for this? They are magnetoacoustic waves which sounds like, a super villain, but it's not. They're just really cool. The thing is, all waves, it needs something to make them and something to break them.
They need a source of energy and input to generate the wave, and then to make the wave finish being a wave, you need some sort of force that pulls the wave back, that tries to make the wave go away. When the case of ocean waves, what pulls them back is gravity. If you make a swell of water, then gravity wants to pull on that swell and say, no. No. No.
No. No. No. Calm down. Get get out of here.
And that, competition between the energy input and the force that's trying to pull it back, trying to restore the normal order is what generates a wave. But out here in the atmosphere of the sun, gravity is not in charge. It's not the lead singer. And so, what generates this ability for waves to to exist is the presence of the magnetic field. Magnetic field lines like to stay parallel.
They don't like disturbances. If you got magnetic field lines, they're just hanging out and then you disturb the plasma underneath them and and you twist the magnetic fields, the first thing they're going to want to do is realign And because of that realignment, if you boom. If you were to hit the plasma, deposit some energy in the plasma, create a disturbance in the force, if if you will, then the magnetic fields are gonna want to say, no. No. No.
No. Just put everything back to normal. I just want to be nice and parallel. I was having a nice day. Okay.
And then you came along and just disturbed it. Oh, I just wanna put it back. That competition between the energy input and the desire of the magnetic fields to be straight makes it possible for waves to exist. So we've got magnetic fields in charge. They're carrying waves, which can deliver energy to and through the corona, but what provides the spark?
What's the source? What's that energy input in the transition region that leads to the generation of waves that then move on through the corona and deliver their energy? This is when the Parker Solar Probe discovered something amazing, switchbacks. I love this. Check this out.
The sun has no solid surface, so we have to start way down in the body. We have to start in the photosphere. We've got those granules, you know, these bubbles of plasma rising to the surface and then slinking back down. These bubbles of plasma generate. They churn up magnetic fields.
Why? Because they're they're plasma, they're electrically charged, and they're moving so that makes magnetic fields. These magnetic fields don't just exist in the body of the sun. They also punch through. They exist in the transition region as well.
Some of the magnetic fields are open. Like, you could imagine the the magnetic field lines just pointing away from the sun and they're like waving in the breeze, like those wacky waving arm flailing guys. They're just waving. And then some of them are closed. They look like horseshoes where the magnetic field lines punch up out of the surface, out of the photosphere, and then plunge back down.
So you've got both kinds because life is complicated. When these two kinds of magnetic field lines meet. When the open kind, that what kind that points straight up, and then the closed kind, the one that look like horseshoes. When they meet up, they get tangled. They disconnect.
They reconnect. There's a tremendous release of energy. Magnetic field lines like to stay parallel. They like to stay away from each other. But when you tangle them up and twist them up, there can be so much tension that they snap and realign themselves, and that that process, that snapping is like when you twist up a rubber band too much and it just snaps, it releases a tremendous amount of energy.
Tremendous amount of magnetic tension gets released. This creates a kink in the magnetic field lines. It's an s shaped kink and that this is the switch back. It looks like a zigzag because it looks like you're you'll follow the magnetic field up and then it will dip down, and then it will curve back up, and so you this little zigzag. It doesn't make that sound.
That that's my own creation. The Switchback doesn't just stay there, it moves like when you when you crack a whip, the wave travels down the whip until it until it reaches the end. Once this switchback is created, it travels as a wave down the magnetic field, which takes it out through the transition region, and into the corona. Eventually, the switchback falls apart. It just destabilizes and it deposits the energy like a wave crashing against the shore.
And this is this is the whole picture. We start in the body of the sun, the gravity dominated body of the sun generating these granules which mixes things up. Then there's the transition region where these magnetic fields get all tangled up with themselves. Sometimes they get too tangled and there's a release of energy creating a switch back, then the switch back travels, follows the magnetic field out all the way into the corona where it dissipates and it releases energy. This is not an efficient process whatsoever.
It does not deliver a lot of energy at all, but it's enough because you only need a little bit of energy in the corona to get things up to a 1000000 degrees. We now believe this is the primary way that the solar corona gets its heat. Waves in the magnetic field that are formed, that are powered by granules in the photosphere, formed in the transition region, and then get to continue living through the corona where they eventually deposit their heat. We care about this, one, because we like interesting mysteries in the universe, and also, like, solar weather is kind of a big deal. The more we understand solar processes, the relationship between gravity and magnetic fields and plasma and switchbacks and reconnection and flares and all that, the better predictions we can make for space weather.
And we care, of course, because magnetic fields are the best. Thanks to Karen P and family, Jim d, Ryan s, and Bob c for the questions that led to today's episode. Please keep those questions coming. It's askaspaceman.comoraskaspaceman@gmail.com. Send me your questions.
I'll put them on the list, and then someday, I'll get around to them. I promise. I really appreciate it. Thank you for all the questions you sent me. It's the best thing.
Every time I get a question from any of you, it is the best thing. It's like Christmas, anytime I get a question. Thank you for leaving reviews on your favorite podcasting platform. It really helps the show visibility, and thank you for all the contributors on Patreon. You really do keep this show going.
That's patreon.com/pmsutter, p m s u t t e r. It it it's my name. I'd like to thank my top Patreon contributors for this month. They are Justin g, Chris l, Alberto m, Duncan m, Corey d, Stargazer, Robert b, Nyla, Sam r, John s, Joshua, Scott m, Rob h, Scott m, Louis m, John w, Alexis, Gilbert m, Rob w, Jules r, Mike g, Jim l, David s, Scott r, Heather, Mike s, Pete h, Steve s, what what word, Lisa r, c, Kevin b, and Michael b. That's patreon.com/pmsetter.
Thank you so much for listening, and I will see you next time for more complete knowledge of time and space.