StarTalk Podcast
Hosted by Neil deGrasse Tyson
See the Sun with new eyes as we discuss the many ways this ball of plasma illuminates our past, present and future.
7,960 words · 5 speakers
Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.
Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk. I'm Neil deGrasse Tyson, your personal astrophysicist, and today my comedic co-host is Chuck Nice. This week, we're gonna talk about something that people have been thinking about for millennia, and we're gonna do a whole show on it. It's on the sun.
Well, you know, I really thought you were going with sex there. I really did, Neil.
Same number of letters, begins with S, the vowel in the middle.
There you go.
Okay.
But the sun is good.
We'll bring you back for that show, Chuck, all right? But remember, this is a science show, had to be the science of sex.
The science of sex works for me.
We'll keep you on the list for that.
But just the sun, most people just think of it as a source of light and a source of heat, but it's a star, one of hundreds of billions in the Milky Way galaxy.
You know, I was very disappointed, probably like most human beings, the day I found out that all the little lights that I saw in the sky at night were nothing more than another version of our sun.
What do you mean, "nothing more than"? This ennobles them from little points of light to entire incandescent balls of gas, and it took centuries for people to figure this out.
Well, you made it sound a lot better than what I said.
Just saying. The sun is millions of degrees in its core, thousands of degrees on its surface, and at those temperatures, atoms lose their electrons, and we have a new word for that state of matter. It's a state of matter where you have atoms that are not complete. They're charged, because you ripped electrons off of them and they run amok in a soup. And we call that a plasma, sometimes referred to as the fourth state of matter.
Awesome.
You might have heard about plasma in your day.
I have heard about plasma, because I'm a huge fan of Star Trek, and they have plasma conduits which actually help the warp engines.
Uh, uh, uh, function, so.
Is that the best explanation?
That's all I know about plasma.
I thought I get a little more technical detail.
No, no, I gotta make you know.
It's plasma thingies and they help it go.
Yeah, they do. They, they, they actually make it move. Plasma. That and, uh, you know, if you break our blood apart, plasma's part of it.
Of course, that's a different ki- that's a whole different word, actually. They just happen to be spelled the same.
Okay. Now, don't forget, there is also the most, um, how shall I say it? Important plasma.
Which is?
The television.
Ooh, the plasma TV.
Which brings me my football on Sundays.
I gotta hear that football voice. Give it to me.
Plasma television, where you watch the gladiators of the Glittern. Watch it.
That, the plasma in your TV is not blood plasma. It actually is related to the plasma on the sun.
Oh, okay.
That's correct. It's, it's charged gas.
Charged gas.
All you need there. And the sun is composed of mostly hydrogen. It's got su- ninety percent of the atoms in the sun are hydrogen. And about eight percent are helium, and the rest is other, my favorite element, other.
Now, from what I understand, we're gonna have to, uh, borrow some helium from the sun because we seem to be running out of it here.
We are running out of helium on Earth.
On Earth.
If we're gonna, I assure you, we're not gonna get it from the sun. We're just gonna run out.
We'll send you there, Chuck.
Nobody, nobody's gonna make that pickup, huh?
So, the sun is manufacturing helium every second of every day of every, I mean, Earth days. Sun has its own day, which actually lasts about a month. Uh, sun takes about a month to rotate.
Really?
Uh, it doesn't, almost make, makes no sense to think of a day on the sun, cause the sun.
The sun is the day.
Is the day, no matter where you are. But the sun takes about a month to ru- but sun rotates.
So, it's going around just like a planet?
But it's a big ball of gas, so it's not all in one piece. It kind of rotates, it's faster at its equator than at the poles. So, it's, it's a kind of, it's a funky situation.
All right, now I have a-
That's got itself in.
I got a real question for you.
What's that?
Real question for you.
Yeah?
You say the sun rotates.
Yeah.
Our Earth rotates around the sun as well as the other-
Uh, Earth rotates on its axis.
On its axis.
And revolves around the-
And revolves around the sun.
We have two different words. Rotate on an axis, revolve around something else.
Okay, so the sun is rotating, we are rotating and revolving. Is the sun traveling?
As it rotates the way we are traveling. Are we all traveling together?
Indeed.
Ooh. So the sun is not only moving randomly among other stars in the solar hood.
Solar neighborhood. There's several hundred stars that together we, among our random motions in the galaxy, together we orbit the center of the galaxy.
So we are actually traveling as a solar system.
About 120 miles per second. As a solar system.
As a solar system.
In orbit around the center of the galaxy, the supermassive black hole that dines upon anything that gets too close.
And we have other neighbors that are doing the same thing.
The whole hood is in orbit around the center of the galaxy.
And what is the closest, um, um, solar system that could go borrow a cup of sugar?
You want to, because it is the hood. Alpha Centauri is a star system. It's about four light years away. So travel at the speed of light, you get there in four years. Four years you come back and your cake is burnt.
Now, I don't want to carry the subject of the sun all by myself.
I mean, I could, but it wouldn't be as interesting as if I've got a real solar expert. I study stars, but as points of light in the nighttime sky.
As any good astronomer does. But the sun, there are people out there who look at the sun with special tools, who study them, who try to understand every burp that happens in the sun and why. We found one.
Yes.
Happens to be visiting New York City. It is Judith Lean. Judy, what, can I call you Judy or is it Judith?
No, it's Judith.
It is, excuse me.
My, my mother insists.
It's Judy to her friends.
No, no, no, it's Judith.
To me, okay. So, welcome. You, you're up visiting New York City, visiting the Goddard Institute for Space Studies, where they study all kinds of solar system, uh, questions, but you're based at the US Naval.
Naval Research Lab.
In Washington DC.
Chuck, it's not your belly button, just.
Okay, I was about to say, this sounds very interesting.
Well, you know, when you fly into National Airport?
From the south. If you look to one side, you see all these big domes, right? That's the Naval Research Lab. Prime real estate on the Potomac River.
And it's a very secure place. So what possible interest does the Navy have in the sun?
Oh, you are not the first person to ask this.
All right.
Okay, so the Navy.
Wait, wait, just to clarify, they do a lot of things there, but you're in the Sun-Earth System Research. Is that, no?
I'm in the Space Science Division and the work that I do is research on the Sun-Earth System.
Connection.
Which is why the Navy cares, because you think Navy like ships, you know, what are they, you know, water, not sun.
Water, right.
Water. I would think that the Navy would be a hell of a lot more interested in the moon, since the moon controls the tides and they're in the water.
Well, it turns out the sun controls tides too, but we'll get back to that in another second.
But this is, hang on, you guys.
They have all these ships, right? And they have aeroplanes on the ships and they have lots of assets and they distribute them all over the globe. And so all these assets need to communicate with each other and they need to track them. Now, how do they do that? They do that with satellites. Satellites are more or less the nerve system for the Navy. The Navy is the biggest user of space. I bet you didn't know that.
No, I didn't know that.
It is, it's the biggest user of space.
Of space assets?
Of space.
Because it has satellites that it uses for communication, navigation.
And, and not to mention those awesome little cruise missiles.
I'm gonna mention them.
But the sun is the driver of what we call the Extended Operational Environment. So where these satellites.
That sounds code, code for something. Extended Operational Environment.
I know, it is. We use it all the time.
It means operations off of earth's surface, up there above the, above the atmosphere.
So the, in the old days, when you were at war, then it was terrain, right? You needed to know the terrain, if there was a mountain or something.
Right.
Now, we call it the environment. And if you're operating in it, it's the operational environment. And if you're operating on the sea, that's like your local operating environment. But because now the assets of the navy extend essentially all the way into space. We call it the extended operational environment. And the sun controls the weather of the environment where satellites orbit, where the radio waves communicate.
Weather is, you're using that term loosely there.
You don't mean, does it rain on the satellites? You mean, is the sun messing with the satellites with its own sources of radiation?
Yeah, I'm using weather and climate even as a terminology for changes in things like the pressure and the temperature, the state of the atmosphere above like a hundred kilometers.
Nowhere where any actual weather that anybody cares about takes place.
Well, if you, if you want to connect like with your iPhone and a big solar storm comes along, smashes all that plasma that you talked about into the earth's magnetosphere.
That would be bad for my communication.
Upsets the satellite that is connecting your communications. Then you do care about the weather in space.
So what you've done is you've built an entire vocabulary that borrows from terrestrial weather to describe what the sun does to satellites. You speak of solar wind, you speak of solar storms, you speak of all of this vocabulary.
Exactly. That's exactly right.
Is there a solar umbrella?
Just wanna know.
That's top secret.
Actually, no. People talk about that in terms of geoengineering for climate change. If you can put a reflective shield to stop some of the sun's photons, the bright energy coming in, then the sun, of course, is in addition to creating space weather, is the primary energy source for the earth.
Drives the earth.
If we didn't have a sun.
Got the steering wheel.
If we didn't have a sun, we wouldn't have a greenhouse effect.
Well, we'll get back to that in other segments, but before we get there, let's start from the beginning. Let's go back in time, okay? We're not the first ones to be thinking about the sun. Folks have been doing this forever. And the most obvious thing the sun does is, of course, it goes around the earth once a day. And this is what everybody thought it did. And they kept time by this. It defined the day. And the sun at different times of the year is not the same height at noon as it is at other times of year. So that affected seasons. People thought deeply about this. And in fact, so has Bill Nye, always a friend of StarTalk. And Bill Nye, I don't know if you know, he's an expert in sundials. I don't know if you knew this. Did not know that. Yeah, yeah.
He's just, he thinks about the sun all the times. Let's check out what he has to say in this week's Nye Minute.
On a show hosted by an astrophysicist, everyone likes to talk about spacetime like it's one thing, and we all know what that thing is. It's easy. It's a combination, you know, of space and time. Well, it always has been because we reckon time with this planet's path through space. Ancient astronomers like Ptolemy of Alexandria were very good at space and time. Ptolemy mapped places in his Mediterranean world astronomically. He reckoned locations, places in space, with time, the motion of the sun. His navigational table of shadows essentially told you what a sundial would say at each city or seaport of interest. With that information, you can find your way from one place to another, even across the trackless cold blue sea.
So I encourage everyone to take a moment or an hour and ponder why the sun's shadow moves clockwise and why in August it's slower than a clock, but then in February it's faster. Shadows don't talk, but they have a lot to say about the sun, space, and time. For StarTalk Radio, I'm Bill Nye, the Science Guy.
The one and only Bill Nye. So he's telling it like it is from that side of the universe. So the sun is responsible for calendar making and, you know, a famous calendar that's been in all the news lately is the Mayan calendar. Yes. It ends its long cycle next year. And we're all doomed. And that's if you think the Mayans were more scientifically literate than we are today. Yeah. And or that they can predict the future in ways that we can't today. But of course, they couldn't predict their own demise. So that would give me a little, that'd make me a little suspicious about this. They saw our end, but not their own. Not their own. Yes. When we come back, much more on the sun. We'll see you in a few.
Welcome back. We're here with Chuck Knight. Chuck, welcome back. Hey, it's great to be here. And we have Judith Lean of the Naval Research Laboratory. She is a solar scientist specializing, of course, in the sun. That sun. Working for the Navy at the Naval Research Lab. Happy to have you here visiting New York and that we snatched you from your busy day visiting the Goddard Institute for Space Studies. Thanks for being here on StarTalk.
Thank you. My pleasure.
We left off talking about the ways people have worshipped the sun in the past. We can't, no, no mention of that would be complete without Stonehenge. Stonehenge, as we all know, at the summer solstice, which in the UK they call the midsummer. The sun rises over what they call the Heelstone there. The problem is, people hardly ever notice this. You know why? No. It's always cloudy.
Bad place to worship the sun. They chose the wrong island, okay?
Yeah, I think maybe the Egyptians might have had a little something on them.
Egyptians.
In that, in that department.
They had a leg up on that one. Uh, so, so, you know, we have a kind of a hinge here in Manhattan. I don't know if you knew that, Judith. We have a Manhattan hinge here. The grid of Manhattan is sort of a rectangular grid, as any grid would be. And what you do is you find the days of the year where the sun sets exactly on that grid. And it's become a celebration. Thousands of people pour into the streets. And what makes it interesting is that the roads are narrow, the buildings are tall, and you have an exact line of sight all the way to the horizon, miles away. So the sun sets at the vanishing point of the steel canyons we call the streets of New York.
I had no idea that that's what they called it. But I know many people, myself included, where there are certain streets on certain days, especially in the summer, where you, there's outdoor bars, like rooftop bars. And you go, and the reason why you go to this particular rooftop bar is because the sun sets in the middle of the street and goes down into the river. And you get to watch the sun disappear between the buildings.
That's your excuse, going to the bar on those days. So, we have some, now, it turns out, those, Judith, I don't know if you knew this, the two days where that happens in New York happen to correspond with Memorial Day and baseball's All-Star break. So I'm imagining apocalyptic earth where they dig up the grid of Manhattan and they try to understand, why did they orient it in this way? It must be because there's sun worshippers and they put their greatest rituals on this grid. It is war and baseball. Will that allow them to understand Americans is the question.
Of course it will. That's, that's pretty much America right there. Yeah, there's not much else. I don't think so. Warren's baseball sums it up. I don't think so. That's all, that's what you got here. And so they're interesting. The sun shows up in a lot of things. There are newspapers that have the word sun in it. The Chicago Sun-Times, the, uh, well, there's the, the Phoenix Suns, the basketball team. Exactly. Because Phoenix, as we all know, is a quarter mile away from the surface of the sun. That's why it's 114 degrees. It feels that way sometimes. In the summertime. But let's talk more about the sun as a physical object. It's, it's the most massive object in the solar system, more massive than all the other planets combined. And it's a big gaupe ball of gas and it is in balance.
Usually when people hear the word balance, they think of a delicate balance. But the sun is not in delicate balance. It's actually in a very stable balance. It's, it's the difference between balancing a pencil on its tip or on a freshly flat eraser on the other side. One, if you did balance it on its tip, it would be an unstable equilibrium. And on the other side, it would be slightly more stable. You know what's really stable? A pyramid. You can't push over a pyramid. True. I was gonna say, how about we lay that pencil down flat? Then it's even more stable than the other two cases. And so all of this is going on in the sun. And we mentioned earlier that the sun does not rotate all in one piece and that it's a plasma. It's a charged gas.
And Judith, tell me what happens when you have a plasma that is not all rotating at the same rate? This is, this is, this can't be good for the star.
Well, it's actually the reason why the star goes through its cycles. Or part of the reason, because the different regions on the sun's surface rotate at different rates. That moves around features on the sun's surface that we call active regions. Magnetic flux bubbling up from below the sun's surface. And this is part of what drives the sun's dynamo. And that's the dynamo that produces cycles of activity in the sun.
So dynamo is the magnetic field being driven by these activities, I guess. Is that fair to say?
The dynamo, it consists of a number of parts. There's the eruption of the magnetic fields onto the sun's surface. There's the rotation.
Wait, wait, wait, let's back up. So the sun has magnetic fields inside. And normally you want to keep them inside, but occasionally they bust out.
They bust out partly because of this rotation.
So you're saying that the sun has zits?
Well, yeah, little black spots.
Little, yeah.
That occasionally busts.
That little, yeah.
Exactly.
I was thinking bust a move rather than bust a zit.
Bust a zit, yeah, the sun needs Clearasil, basically.
The magnetic flux just pops up into the sun's surface and we see a spot, a blemish.
Cool.
Yeah, it is cool.
And I think I got this right. Isn't it true that because it's magnetic fields that drive this? All sunspots are either positive magnetic field or negative, so they come in pairs. Is that correct?
In fact, they do. And in fact.
I get a gold star for that.
You do. And in fact, in a regular sunspot cycle, one of the 11 year cycle, there will be a spot that has one polarity, let's say positive, leading a spot that has a negative polarity.
And it's. Across the surface of the sun.
And then when the next set of 11 years comes by.
Well, what happens is that, well, we talked about the sun's rotating. So that separates these different spots a little bit. If there are different latitudes on the sun's surface.
So there's a shearing effect.
A shearing effect, exactly.
The equatorial ones beat the other ones around.
More or less, but it's more complicated than that. Because there's also what we call a meridional flow. It's a flow from the sun's equator to its poles. And so that transports different spots of different polarity. And some of them come to the poles. And then they get sucked down back below the sun's surface and that. Completes the cycle of the dynamo.
So sunspots lead an active life. Yeah.
And what's more, they reverse every solar cycle.
So let me add that, just to put things in context, if the sun were hollow, you could pour more than a million Earths inside of it and still not fill its volume. Holy moly. And that should tell you that these little blemishes we call sunspots. Right. In fact, typically are larger than the entire Earth. So these storms that Judith is telling us about are larger than the entire planet that we call Earth.
People, let me just, for the sake of completeness here.
Good.
Spots are things that everyone knows about. But there are many other regions on the sun's disk. Some of them are called plages.
Plages.
Plages. And that comes from the French word for the beach, because they're bright regions. And others are called faculi.
Faculi.
Faculi, and that comes from the Italian word for torch.
How would an American say that? Because your Aussie accent. Very carefully on the radio.
Okay, look, it doesn't matter what you call them. Just think of the sun as having lots of different features on its surface.
So plages and faculi.
And they're bright. Sunspots are dark, but there are bright regions on the sun as well. Big, bright regions.
Let's find out. You know, I spent some time at the National Solar Observatory. And guess what the name of the town is? Sunspot, New Mexico. Did you know that, Jack? No, I did not. You can actually get a date stamp on your mail. It says, Sunspot, New Mexico. And I sat down for StarTalk and chatted with the director of the National Solar Observatory just to find out what it takes to observe the sun as a professional. I'm gonna go with sunglasses. Check in with my interview with Steve Cale, director of the National Solar Observatory.
Our primary function is to study and understand the sun. So all our telescopes work during the day. And what I'm working during the day is the sky's pretty bright. So you gotta make a specialized telescope to see the sun.
Because as an astrophysicist, as you know, our biggest problem is the lack of availability of light. So we've got to build really big telescopes to detect the dimmest things that are out there. And meanwhile, you're working with the very brightest thing out there. And so you have no shortage of light to work with.
No, it's actually kind of the opposite because when we look at the sun, we like to look at very small pieces of light and we like to look at them simultaneously with four or five instruments. So by the time the light gets to the camera, we're in the same situation as the nighttime folks.
You're saying you slice and dice the sun's light to your needs and by the time you're done, there's hardly any light left to use?
That's right.
I still don't have sympathy for you.
Yeah, I don't have sympathy for solar because I'm a deep dark sky observer of dim things.
And here he is throwing away photons of light, just slicing and dicing the sun. Just to... So I'm jealous, actually.
He's not throwing it away. He looks at different wavelengths and that tells you different things about the sun's atmosphere.
So all those gases, all those molecules and charged species in the atmosphere, they radiate at different wavelengths. So he just picks a little bit.
Well, that's an interesting point, which we'll get back to later in the broadcast because the sun is not just visible light, there's much more going on there. And I want to find out how that interacts with Earth. You know, one of the best ways you can see the outer atmosphere of the sun from Earth is during a total solar eclipse.
Ah.
Have you guys ever seen one? Judith, have you seen one?
I never have.
You've worked on a sun?
No way. Get out of here now. Go, go.
And I have, and I've not seen an aurora, which is another impact. I know.
Oh my.
You, what? How? How? What? How this?
But I love sitting in the sun. I grew up in the desert in Australia. Doesn't that count as something?
Chuck, have you ever seen a total solar eclipse?
Okay, watch this. Watch this. Yes, I have.
Chuck has.
I have seen a solar eclipse.
When and where?
I don't want to say when because it'll date me. You'll know exactly how old I am.
We'll get back to that after the break. This is StarTalk Radio.
Welcome back. I'm here with Chuck Nice.
I am flabbergasted.
Good to always have you here.
I'm good to be here.
Next to me in these times of need.
And let us not forget our special guest Judith Lee, a solar researcher at the Naval Research Lab. She's here because we're talking about the sun.
Which is right.
I know a little bit about the sun.
She knows more.
That's why we've got her here. We left off Chuck, you were boasting that you had actually seen a total solar eclipse back in 18...
What... Okay, you don't tell us what year, but where were you?
I'll tell you what year.
And that'll tell me what year, because I know where they all were.
You'll know where exactly. I was in Philadelphia, so you'll know.
No, actually, I'm sorry, I can't... You're actually from Philadelphia?
Yeah, I'm from Philadelphia.
Total solar eclipse?
It was a total solar eclipse.
Very nice.
And it happened in the afternoon, I remember, and...
I'm glad it happened in the day, because it wouldn't have happened at night for you.
But I have to say, you know, sitting next to Judith and hearing her say that she's never seen one, I feel very special, but I'm also perplexed that all you do is study the sun and you haven't seen a solar eclipse. How's that happen?
The most beautiful, splendiferous thing ever.
No, no.
You must be a theorist.
We have these fantastic instruments, and in fact, the Naval Research Lab currently has these most beautiful instruments looking at the sun and the energy that it spews out and the images that we collect of the sun from these instruments are so beautiful.
So what she's saying is that all the action is happening behind the moon during an eclipse. So you don't even need the moon to help you see the sun.
Well, one of the instruments that we built at the Naval Research Lab, well, I didn't build it, but the expert, experimentalist did, literally puts an artificial occult in the optical...
You create your own eclipses.
Exactly. And that's what, that's how you see the outer atmosphere of the sun. And what's more...
Hate to disappoint you there Judith, but I've actually seen the real thing.
But you haven't seen it.
Yeah, but you're right, I didn't.
But you don't see it every minute, minute after, minute after, year after.
She doesn't have to wait around or travel to some exotic place.
You can dial it up, all you have to do is Google.
Yeah, so in this, in your studies, the eclipse that I saw happened to be near a solar maximum, where there are many sunspots, and so the corona, the atmosphere of the sun, which is laid visible, rendered visible when the disk of the sun is blocked by the moon during a total solar eclipse. It was huge. So all I can think of is that the sun is, is cycling in its energy that it sends to us. And this is what you study, isn't it?
Absolutely.
And so sunspots, more sunspots, it's peak, and less sunspots, it's, it's quiescent, right?
And we are supposed to be approaching a sunspot maximum next year. But last I checked, the sun has not been delivering on, on the promise. What's going on there?
Okay, so what happened was, we've just come out of solar cycle 23. Now, these cycles were numbered back 11 times 23 years ago. Solar cycle 23 lasted for a year or two, maybe two years longer than we thought it would.
So longer than the 11-year average.
Now, no, actually, that's an interesting point. 11 years is really the average of the whole 23 cycles. The last two cycles that we've observed from, you know, with all of our fancy instruments, have actually been more like 10, a little bit shorter than 11.
Okay, so it's an average, as we say statistically, it's an average with high variance associated with it.
Right, and so what we're seeing now, we did see this longer cycle. And, and that means that the rise to the next maximum, which is solar cycle 24, is delayed. So it's, it's later than you thought it would be.
But, but, now, one of, one of the scientists that I work with, he thinks it's because we haven't been studying the sun. With all of our fancy instruments for more than a couple of solar cycles. You could look back in the past and there were cycles that were long like this. There were times when the cycles disappeared. So there's a lot of worry and anxiety about are we going into a long minimum? And what's happening to the next cycle? But that's just because we haven't.
It's because you know too much now. Your data are better than ever before. So you get to think about the sun more deeply than anyone, any of your predecessors could.
I asked a similar question of Steve Cale, the head of the National Solar Observatory. Okay. And let's see what he says about this odd minimum we're in now in the history of solar cycles. Normally, when the sun goes through a period of creassence, the number of sunspots drops off slowly and hits some minimum and then comes back. And lately, we haven't seen any.
Well, we've seen a few new cycle spots, but they're, they're smaller than we're used to. We've seen this solar magnetic field reverse, so we know the cycle is chugging along, but sunspots seem to be getting smaller and dimmer.
And does this concern you? Where are you hiding the sunspots?
Well, you know, we're hiding them down at the bottom of our big telescope now. No, in reality, so the solar cycle we know is 11 years. That's more 11 years, plus or minus about three years. I mean, some cycles have been as short as eight years and some as long as 14 years.
So you're saying we have fewer than what you'd expect in a normal 11 year cycle, but maybe this last cycle was just a little longer than you'd expected.
Yeah, this may be one of those unusually long cycles. Or we may be going into something like the monder minimum back in 1645, when sunspots disappeared for about 50 years.
If you read up on the monder minimum, Europe was steeped in what they called a mini ice age, where they were skating on the River Thames in London in the winter, a river that hardly ever, if ever freezes. So are you saying we're ready to plunge into a new kind of winter?
Well, that's not really clear right now. So during that period, sunspots were gone for so long that the overall solar brightness was down a little bit.
So you're saying the brightness of the sun correlates with the number of sunspots that are on the surface?
Right. So the more sunspots on the surface, the more active the sun is becoming. It's a little bit warmer, the chromosphere heats up, we get a little more light.
It sounds a little opposite to what you'd expect, given that sunspots are cooler regions of the sun and they're darker. And so you'd think the sun's total energy would be less. But I guess what you're saying is the rest of the sun is more energetic and it more than handily makes up for this.
That's right. So that energy that is blocked by the sunspots has to get out somewhere. And it does, but because there's more magnetic field present, that heats the rest of the atmosphere. And so we get a warmer sun. And we're not talking much, less than a percent.
Is a percent enough to plunge Europe into an ice age?
Yeah, it certainly could be. The Earth itself has so many variables, volcanoes, CO2 emission. And the sun also affects the chemistry of the upper atmosphere. And so you can get feedback mechanisms that could be really strange.
Judith?
Well, remember we talked about bright regions?
Faculi, plage. The reason that the sun's brightness, its overall energy that it sends the Earth, is higher when there are more sunspots, is because the faculi, or the bright regions, dominate over the dark regions. So the sun, the net energy from the sun, is actually this competition between a reduction in the brightness from the sunspots and an enhancement in the brightness from these big, bright regions. And the bright regions win.
Now, what I want to know, however, is that when the sun gets brighter during solar maximum, it's not that much brighter. I'm told that it gets even brighter in some invisible parts of the spectrum, like the UV.
In the, in the total solar brightness, in other words, the radiation or the photons at all wavelengths, it gets about one tenth of a percent brighter. Okay, now before you say, oh, that is so boring.
That's so small and boring.
The energy from the sun is so big that a tenth of one percent of that energy... Is still a lot of energy.
Doesn't matter where that energy comes, if it's visible or ultraviolet, because the ultraviolet affects people how much SPF tanning lotion they use.
Well, you know, the sun is a black body. It's hot, as you said, it's about 10,000.
But we have to clarify, black body.
Yeah, I was gonna say.
Oh, sorry.
In the hood, that means something different.
She just told me the sun was a brother. I was like, whoa, I never knew that.
Oh, my goodness. It's a classic radiator.
So black body is a classic radiator.
If the sun is about 10,000 degrees Fahrenheit, the spectrum, in other words, the wavelength where it produces most of its radiation is the visible spectrum. It's the visible light. And we're very lucky because if the sun had a different temperature, we wouldn't have all that visible light. And our bodies and our planet is tuned to visible radiation. So most of the radiation is in the visible part of the spectrum.
But I would say that if the sun peaked somewhere else, then the whole planet would have targeted to that, right?
Oh, I don't know.
Our eyes peak.
Speculate. But no, so which comes first then?
The sun came first. I got that one figured out. So.
There you go then.
Wait, so, so are you suggesting that during solar maximum, where the UV is a little higher, people need to be a little more cautious? People with lighter skin, more sensitive to skin cancer and ultraviolet, they have to be more cautious about using sunscreen?
Well, yes and no. Yes, but not for the reason that you suggested.
Really? Okay, what's the reason?
So the sun produces more energy in the visible, in the ultraviolet part of the spectrum, you know, in the UVA and the UVB radiation. That reaches the earth's surface. But the reason that it just reaches the earth's surface and is not absorbed, like all of the very extreme ultraviolet radiation, is because we have an ozone layer.
We gotta love the ozone.
Yeah, and you know what makes ozone? The sun. You didn't know that. The sun makes ozone.
So wait, let me get this right. The sun is actually protecting us from the sun.
From itself.
That sounds like extortion. The sun's a mobster.
You should be glad it is.
I gotta tell you something right now. You never know what could happen to your business. It could be a terrible accident here, a fire, anything could happen.
I'll protect you from my people.
OK, now back to the ozone. So the sun makes ozone. And when the solar activity is high, there's more ultraviolet radiation. There's more ozone. So that actually does protect us. So we receive different amounts of ultraviolet light, more because the ozone varies than because of the sun's ultraviolet radiation.
Interesting, I did not know that. And for those who missed the day in chemistry class, ozone is oxygen three ways. It's a three molecule. It's a three atom molecule. O3 is ozone. And it gets zapped by ultraviolet light. It eats the ultraviolet, preventing it from reaching Earth's surface. We've got to take a quick break, but more StarTalk when we return.
Welcome back. I'm here with Chuck Nice. We also have with us Judith Lean, a solar scientist from the Naval Research Lab, because today's topic is, of course, about the sun. And we left speaking about the Molder Minimum, this period in Europe where it was like a mini ice age. It was cold and happened to correspond with a period of low sunspot activity, just as it is now, which makes people wonder, would the global warming phenomenon be even more severe if we weren't going through this sunspot minimum? Judith, do you have any sense of that?
There's been a lot of speculation over many decades about the sun's rolling climate. And a lot of it is speculation.
So the climate is earth climate, not solar climate.
This is earth climate now. But in the last thirty years, we've had instruments, you know, those instruments that measure things from the sun. They've been measuring the brightness of the sun. So we know it changes by about a tenth of a percent. And we can see that this impacts the earth's surface temperature, the global temperature of the earth, by about a tenth of a degree centigrade. So it's not big compared to the effect, for example, of greenhouse gases over the last thirty or forty years.
Okay, so it's interesting, that's important. So you gotta know what matters and what doesn't in the equation.
In fact, you really do have to matter now because in the last probably eight years, there's been a lot of talk about why hasn't the global temperature been warming? Why haven't, you know, has greenhouse gases stopped warming? It's because over the last maybe six or seven years, the sun has been in a descending phase of cycle. So it just simply stopped for a little bit, the net warming.
So it's on pause mode right now.
It's helping us, basically.
It's helping us.
The sun is like, I'm gonna help you guys out.
But only, it can only do it a little bit. And now solar cycle, the solar cycle is starting up again. So it's gonna be just warming a little bit, only a small amount compared to what we're seeing from.
So the solar cycle is not only about sunspots, it's about explosions on the sun that blast and burst and burp forth plasma pies into space, some of which head towards earth. These are charged particles at high speed. Judith, what gives?
So, okay, so we had the.
Can we blame you? I don't wanna blame you.
So we, so we had these little eruptions, right? And they form these little spots. Sometimes these, the fields that contain the spots.
These eruptions are coronal mass ejection?
No, no, I'm getting there, I'm getting there.
We're not even there yet.
No, no, no, they come from the surface and they break open. So the, instead of the field lines making a spot, they'll break open and extend into space.
The sun busts a move.
Yeah, exactly. And so that, so that means the atmosphere of the sun, in other words, in the corona, the anoramacy, can just flow freely to earth. And it does, it literally is a perturbation.
Well, it flows everywhere in space, occasionally towards earth.
Right, sure. I'm so earth centric.
She thinks the sun is just talking to us.
I know.
The sun has the whole solar system to care about.
I know, I know. But I'm a solar terrestrial sign. Sun earth.
Let's find out what Steve Keel has to say about this sun-earth connection and the storms that it might cause.
We make daily forecasts, but our accuracy is about the same as the weatherman around the turn of the century, so.
Okay, okay, so the question wasn't whether or not you make the forecast, it's what, yeah, how good is your precision? So that's a measure of how little we still know, how much more we still need to learn about the sun.
Right, you know, if you think about earth weather, what makes the forecast accurate now is persistence of the weather and we can measure where it is at any given time. We're getting there with the sun. So like solar sentinel sees mass coming from the sun before it gets to the earth.
Solar sentinel is a, is a satellite.
It's a planned mission. Stereo, which is kind of a precursor to sentinel, gave us that capability for a while. It sees stuff coming off the sun.
Stereo, is that, other than the word itself, presumably that's an acronym for something?
Right. I have to take wild guess.
Yeah, I guess the first S stands for sun, is my bet.
If you're saying today's solar weather prediction is about what earth weather prediction was a hundred years ago, a hundred years ago, they were reading sort of bear fat in a jar, you know, the rheumatism in the knee. So do people come to your office and say, check your arthritis and decide whether what the sun is going to do? You give us another century, how much longer are you going to take?
The accuracy now of the current 24 hour forecast is somewhere on the order of 70% for weak flares and about 50% for strong flares.
And we need to know this also for long-term space exploration. You're going to send astronauts to Mars and they're in a spacecraft for a year. They're basically bare assed out there in space. It's susceptible to solar radiation. They're gonna need to know your forecast in the interest of their health and survival.
That's right. So if they had a good forecast and they knew there was a solar storm headed their way, they could move into a part of the spacecraft where they're more protected. You know, so protection means weight. And so there's a trade off.
The weight of some shield that they might have to carry with them.
Right. So there's always a trade off between how much protection you can put in. You know, how much weight you can launch.
Or you just get astronauts who are on a one way trip and then we don't have to worry about it.
A one way trip. Did I say that in my interview? So Judith, so are these as bad as everyone say they are? These blobs of plasma headed towards Earth?
The blobs of plasma head towards Earth and they disrupt the protective magnetic shield of the Earth. Now, the Earth has a magnetic field, just like the Sun, and it protects to some extent this solar wind rushing.
So it guides the bad particles around us so it doesn't hit us?
But when there's a big storm, that smashes into the Earth.
A sun storm.
A big sun storm. It smashes into the outer environment of the Earth and that disrupts this protective shield.
And this is when you get your aurora, I bet.
You do?
Your northern lights.
And what happens there is...
And you're from Australia, what they call it, what, in the south?
I don't know.
You could say the southern lights. The aurora Australis.
Aurora, I don't know.
It's even named after you guys, the Aurora Australis.
Oh, I'm trading her in.
She hasn't seen an eclipse, she doesn't...
I'm gonna rename it. I'm gonna call it a beautiful bitch slap.
So, so, so we're running very short on time here. So, so it's a real danger for astronauts. They have to have some kind of shielding for this, right? But Earth has built in shielding, it's a magnetic field.
Right. So when you go outside, whether you're an astronaut or a spacecraft, if you go outside the magnetic shielding, then you get bombarded with these energetic particles that can do a lot of damage.
So maybe what we need is a way to put a magnetic field around the spaceship. That would be cool. And then make them have their own aurora at night, you know? It would be just kind of cool.
Works for me.
It's all the time we have, but I want to thank my guests. And as always, I bid you to keep looking up.
The
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