NASA’s Curious Universe

Season 3, Episode 5:“Plasma, Plasma, Everywhere!”

Tentative Release Date: Monday, August 9

Estimated Run Time: 18:53

Introducing NASA’s Curious Universe

Our universe is a wild and wonderful place. Join NASA astronauts, scientists and engineers on a new adventure each week — all you need is your curiosity. Go asteroid hunting, explore faraway galaxies, and observe a black hole as it begins to form. First-time space explorers welcome.

About the Episode

The night sky is full of planets, satellites and cosmic objects we can see with our eyes and telescopes. In between all that material there’s a huge amount of invisible matter and the vast majority of it is called plasma. Follow along with scientists Doug Rowland and Don Gurnett, as we journey through this mysterious and electrifying substance.

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Doug Rowland

We think of space as being empty.

[Song: Light at the End 4 Underscore by Goodman Krause]

Doug Rowland

And I don’t mean like planets and stars, of course those things are out there. Even the space between the planets and the stars is full, and it’s rich and it’s dynamic.

Doug Rowland

You get all these different charged particles of the gases, of the plasma, the electric and magnetic fields, you get radiation, you get dust, you know, you got all these different things up there.

Doug Rowland

And yeah, they’re so rarefied that you don’t see it from the ground with your, with your eye…there’s this big invisible population.

Doug Rowland

So space being empty, is the biggest misconception. I think it’s just, it’s full. And it’s important. And it’s interesting. Just so many things that if we could see them, they’d be on the wall of every art museum. I mean, they are just glorious, some of these things.

[Theme Song: Curiosity by SYSTEM Sounds]

HOST PADI BOYD:This is NASA’s Curious Universe. Our universe is a wild and wonderful place. I’m Padi Boyd, and in this podcast, NASA is your tour guide!

HOST PADI BOYD:You’re probably familiar with three states of matter – solids, liquids and gases, like ice, water, and steam.

HOST PADI BOYD:Beyond gases, there’s another state of matter called plasma. And it makes up 99.9% of the observable universe. This is completely different from plasma in our blood. We’re talking about a state of matter, that’s similar to a gas but with different properties.

HOST PADI BOYD:We actually don’t see this kind of plasma very often on Earth, but when we do, it can be in beautiful and exciting ways.

[Song: Snow Blanket Instrumental by Parsons]

HOST PADI BOYD:So what is this substance that is so common in our cosmos but still puzzling scientists here on our home planet?

HOST PADI BOYD:Today, we are taking you on a tour of plasma – what it is and where we can find it. But before we get out in the expanses of space, we have to start really, really small…

Don Gurnett

My name is Don Gurnett. I’m an emeritus professor at the University of Iowa Department of Physics and Astronomy, where I’ve worked for something close to 65 years. I’ve been other places in between, though.

HOST PADI BOYD: Don Gurnett has spent his career studying plasmas and plasma physics. To begin talking about plasmas, you have to start with a gas. And to turn that gas into a plasma, we’ve got to add a little bit of energy.

[Song: The Mad Scientist Underscore by Ravel Chapuis]

Don Gurnett

On Earth’s surface, we don’t have any significant amount of plasma, we have neutral gas, thankfully, because plasma would probably cause you health problems.

HOST PADI BOYD:Like all states of matter, a plasma is made up of atoms or molecules that have been excited with energy. Those atoms are made of three different particles – neutrons, protons and electrons.

HOST PADI BOYD:In a neutral state, an atom or molecule has the same number of positively charged protons as negatively charged electrons.

Don Gurnett

If you could strip the electron off of the atom so that the electrons are free, then you have electrons and positive ions, that’s called a plasma.

Don Gurnett

So you might ask the question, how do you strip the electron off of the atom? And there’s at least 2 ways that I’ll mention. One is to heat the gas up to a very high temperature, so high that the vibration of the molecules will break off an electron. And that happens when you get an ordinary gas to a high temperature like in a flame. If you get up to like 1500 or 2000 degrees, there’ll be a bit of a plasma there.

Don Gurnett

Under more extreme circumstances, like an electric arc welder, you know, which makes a big spark. Well, that’s a plasma actually.

HOST PADI BOYD:While most plasma is found out in space, there are a few instances where you can find it right here on Earth. Some of them you probably see every day and others are more of a rare occurrence.

HOST PADI BOYD:On a daily basis, you can find plasma in fluorescent lightbulbs, plasma screen tv’s, and neon signs… but these are pretty small and contained cases.

HOST PADI BOYD:We don’t start to see bigger instances of plasma until we head up, into the Earth’s atmosphere.

[Song: A Greater Tomorrow Instrumental by Panades Garcia]

Don Gurnett

When a lightning discharge occurs, you know, you see that flash across the sky? Well, that flash is caused by an electrical current, which heats the ordinary gas up to a very high temperature and makes a plasma column, which glows. And that’s what you see as the lightning flash.

Don Gurnett

That example tells you another important thing about a plasma compared to an ordinary neutral gas. A plasma conducts electricity. And that’s what makes a plasma really different from an ordinary gas- it involves electricity and magnetism effects.

HOST PADI BOYD:It might be hard to conceptualize a plasma, because we don’t interact with them very often, compared to a solid, liquid or gas.

HOST PADI BOYD:But a plasma is very similar to a gas until you start looking at the magnetic or electric principles. This can make for some pretty strange effects, and some pretty complicated science.

HOST PADI BOYD:Electric and magnetic fields are all around us, but they don’t typically affect solids, liquids, and gases we interact with. They do shape plasma.

HOST PADI BOYD:And the further we start to get away from Earth’s relatively neutral surface, the more often we can find these electrically charged gases.

[Song: Gear Wheels Underscore by Ravel Chapuis]

Doug Rowland

Hi, I’m Doug Rowland. And I’m a scientist studying the Earth’s upper atmosphere. And that’s an interesting region, because it’s where the Earth’s atmosphere that we breathe, turns into a gas called plasma that’s electrically charged.

HOST PADI BOYD:Doug studies the layers of gases in our Earth’s atmosphere as we move out toward space.

Doug Rowland

So once we get beyond our lightning and the things that happen right here on the ground –the first plasma you’d encounter would be something like 50 miles overhead. And it’s different during the day and at night.

Doug Rowland

During the day there’ll be plasma at those altitudes, and that’s generated as the sunlight shines on that gas. It’s very tenuous gas. So there’s sunlight shines on it, the ultraviolet light breaks those atoms apart.

Doug Rowland

At night, there’s no sunlight. So depending on where you are in the world, there’s no other source of ionization. So at night you wouldn’t see plasma that well.

HOST PADI BOYD:One of the reasons plasma doesn’t last long here on Earth is because those atoms generally stay in their neutral form…and ions and electrons quickly come back together if they have been separated.

HOST PADI BOYD:However, with stronger forces from the sun and fewer particles in our upper atmosphere, the ions and electrons don’t come back together as quickly, resulting in an extended state of plasma.

Doug Rowland

As you go up altitude, the plasma can last for longer. So once you generate it with the sun shining on it, once you get up to say 100 miles or 200 miles, that plasma can live for a long time. So even after that part of the Earth’s atmosphere rotates into the night side, you can persist for a long time.

HOST PADI BOYD:There’s another way plasmas can be formed besides separating atoms or molecules… and that’s by adding extra electrons to a neutral gas.

Doug Rowland

You can also create plasma by slamming into them with other particles, like electrons. The way the Aurora are created, is you get electrons coming in from outer space, and they get shot down out of outer space into the atmosphere.

HOST PADI BOYD:The Aurora, which you might know as the Northern Lights or Southern Lights, are beautiful displays of light in the night sky. These shifting sheets of light and color in our Earth’s atmosphere appear mostly near the north and south poles.

HOST PADI BOYD:They can come in a wide variety of shapes and colors… and they happen when electrons from space collide with atoms in the Earth’s atmosphere.

[Song: Aurora Underscore by Peterson]

Doug Rowland

And when they do that they run into gas molecules, gas atoms, depending on what it is. And they can do two things. They can excite those atoms or molecules and make them emit light, like red light or green light like you might see in the Aurora. And they can also sometimes break those atoms or molecules apart and make your ions and electrons.

HOST PADI BOYD:The beautiful Aurora are a visual side effect of some of the particles in Earth’s atmosphere turning from a neutral gas into a plasma. But seeing the aurora isn’t the only way we can experience a plasma.

Don Gurnett

I have gotten into kind of an unusual area of research, and that is to study waves in plasma.

[Song: Hedera Helix Instrumental by Dury]

HOST PADI BOYD:Again, this is professor Don Gurnett.

Don Gurnett

You see I’m talking here, sound waves, that’s the way I’m speaking. Plasma also has it turns out, a wide variety of waves that can propagate in a plasma, we call them plasma waves.

HOST PADI BOYD:Since his time as an undergraduate at the University of Iowa, Don has been studying all the different ways we can hear plasma.

Don Gurnett

And way back in, like 1961, we had a visitor come here and play some unusual sounds that they detected on the ground, things called ‘whistlers’. And I got very interested in this and I decided to build just down in the basement of the physics building just for fun, I was an undergraduate engineering student then, and I built this receiver to try to detect these radio waves from space that people didn’t know much about.

[Sounds of bustling city]

Don Gurnett

Couldn’t use it around the city because the city has so much 60 hertz powerline noise. So I took my receiver out to my father’s farm, and we turned all the electricity off.

[City sounds end]

Don Gurnett

And at first I remember I was disappointed because I didn’t hear anything but just kind of a hissing noise, which is noise of the receiver. But then I think it was on the third night I heard very distinctly. (whistles) I can’t mimic that very well, but that’s what it sounded like. So this was really exciting not only to me, but a lot of people.

HOST PADI BOYD:And there are a lot of different things we can hear once we pick up sounds of plasma waves, including whistlers, hisses, and choruses.

HOST PADI BOYD:This is a whistler wave {play whistler wave}. Sounds pretty spacey, right?

HOST PADI BOYD:If you’ve got the right antenna out, you can hear those around lightning strikes.

HOST PADI BOYD:A chorus wave {play chorus wave} happens when loose electrons hit a plasma.

HOST PADI BOYD:And a hiss… {play hiss wave}

HOST PADI BOYD:…Well, we’re not yet sure what exactly causes a hiss but it could be similar to a whistler wave or a chorus wave. Analyzing sounds can help scientists better understand the different ways plasma behaves.

[Song: MYsterious Black Cloud Underscore by Ravel Chapuis]

HOST PADI BOYD:There’s still a lot to learn about this mysterious substance, especially when you think about how much there is out in the observable universe.

Don Gurnett

So it turns out that almost everything in our universe above an atmosphere altitude of about 100 kilometers, is a plasma. Some people estimate that 99.9% of everything in the universe is a plasma.

HOST PADI BOYD:As we continue out on our plasma journey, the most significant source of plasma in our solar system… is the sun.

Don Gurnett

The sun is very hot, and it’s a plasma.

HOST PADI BOYD:Stars, like our sun, are made of very hot gasses. The sun is sohot that most of its gas has been ionized into a plasma.

HOST PADI BOYD:When those plasma particles leave the sun and head out in all directions into space, we call that solar wind and we now know that every planet in our solar system encounters some of that plasma.

Don Gurnett

We must talk about Voyager.

[Winding tape sound, click]

Voyager excerpt: “In the late summer of 1977, 2 unmanned space craft, Voyager one and two, lifted off from Cape Canaveral atop Titan Centaur rockets”

[Rocket launch sound]

HOST PADI BOYD:The Voyager 1 and 2 spacecraft were launched in 1977 and have explored further into space than anything else we’ve sent out into the universe.

[Rocket launch sound]

Voyager excerpt: “Traveling uninterrupted through interstellar space, the Voyagers will endure forever, long after everything man has ever built has crumbled into dust.”

HOST PADI BOYD:The Voyagers journeyed to the furthest planets in our solar system.

[Song: Nebula Main Track by Williams]

HOST PADI BOYD:They were also the first objects to go beyond the boundary of interstellar space — where the plasma from our Sun gives way to the plasma that fills the space between the stars.

Don Gurnett

Well, we flew by with Voyager with a plasmawave instrument for the first time. We flew by Jupiter, Saturn, Uranus, and Neptune with Voyager two – Voyager one only went to Jupiter and Saturn. At those flybys, we detected many of the same things that we detected at Earth.

[Jupiter whistler wave plays]

Don Gurnett

That was the first evidence of lightning at a planet other than Earth.

HOST PADI BOYD:So we now know that plasmas can be found in Earth’s atmosphere, the sun, and the lightning strikes of other planets. But where is this 99.9% figure coming from?

HOST PADI BOYD:You have to remember that space is really big, and so much of our universe isn’t made up of planets or stars but is the really really vast spaces in between those objects.

HOST PADI BOYD: Most of interstellar space – the distances between solar systems – is full of hydrogen and helium plasmas. These interstellar plasmas are the result of exploded giant stars, millions of years ago. Overall, plasmas make up more matter than all of the solids, liquids, and gases in our universe combined.

HOST PADI BOYD:It’s fascinating to look into the night sky and remember that the stars and the spaces between them are mostly made of this wild and energetic substance.

HOST PADI BOYD:Here on Earth, we’re surrounded by solids, liquids, and gasses. And on a much larger scale, we’re actually surrounded by plasmas. Our journey through this fascinating 4th state of matter started at some of the smallest particles, and ends with the vastest distances in our universe.

HOST PADI BOYD:And isn’t it wonderful that there’s still so much to learn?

[Song: Curiosity Outro by SYSTEM sounds]

HOST PADI BOYD:This is NASA’s Curious Universe. This episode was written and produced by Christina Dana. Our executive producer is Katie Atkinson. The Curious Universe team includes Maddie Arnold, Kate Steiner and Micheala Sosby, with support from Emma Edmund and Priya Mittal.

HOST PADI BOYD:Our theme song was composed by Matt Russo and Andrew Santaguida of SYSTEM Sounds.

HOST PADI BOYD:Special thanks to Calla Cofield, Sarah Frazier, Miles Hatfield, Ryland Heagy, Joy Ng, Nick Tomlonovic , Lina Tran and the heliophysics team.

HOSTPADI BOYD:If you liked this episode, please let us know by leaving us a review, tweeting about the show @NASA, and sharing NASA’s Curious Universe with a friend. Learn more about plasma and heliophysics by visiting science.nasa.gov/heliophysics.

HOST PADI BOYD:Still curious about NASA? You can send us questions about this episode or a previous one and we’ll try to track down the answers! You can email a voice recording or send a written note to NASA-CuriousUniverse@mail.NASA.gov. Go to nasa.gov/curiousuniverse for more information.

Doug Rowland

Well, my dad was an engineer back in the day, and he was always building things. They were kind of very concrete things like we built a TV antenna for our for our house, we got television back in the day before cable, we built things like that. And when I went to college, I said, ‘Well, I want to do something technical’, but I wasn’t sure what. And I heard that a summer internship program was opening up for a team that was doing balloon research. And this was a group that was doing astronomy. I said, ‘Astronomy, what does that have to do with balloons?’ And it turned out they were doing gamma ray astronomy. And they developed a new kind of camera that could take pictures of the universe in gamma rays. And they flew it on this gigantic balloons out of Fort Sumner, New Mexico. And they needed a roadie. And I said ‘I’m going to be the roadie. I’m going to go along and drive the truck basically for them and carry all their stuff.’ And it was really fun because we got to get to see like kind of a small group of people who really dedicated, really excited about something, working really closely together at a high level of performance and just having that camaraderie. And so it’s really the people that attracted me, not the science, per se.