Plasma, Plasma, Everywhere!

01We think of space as being empty.

02And I don't mean like planets and stars.

03Of course, those things are out there.

04Even the space between the planets and the stars is full and it's rich and it's dynamic.

05You get all these different charge particles of the gases, the plasma, you get the electric and magnetic fields, you get radiation, you get dust, you know, you get all these different things up there.

06And yeah, they're so rarefied that you don't see it from the ground with your eye.

07There's this big invisible population.

08So space being empty is the biggest misconception.

09I think it's just, it's full and it's important and it's interesting.

10Just so many things that if we could see them, they'd be on the wall of every art museum.

11I mean, they are just glorious, some of these things.

12This is NASA's Curious Universe.

13Our universe is a wild and wonderful place.

14I'm Patti Boyd.

15And in this podcast, NASA is your tour guide.

16You're probably familiar with three states of matter.

17Solids, liquids, and gases, like ice, water, and steam.

18Beyond gases, there's another state of matter, called plasma.

19And it makes up 99.9% of the observable universe.

20This is completely different from plasma in our blood.

21We're talking about a state of matter that's similar to a gas, but with different properties.

22We actually don't see this kind of plasma very often on Earth.

23But when we do, it can be in beautiful and exciting ways.

24So what is this substance that is so common in our cosmos, but still puzzling scientists here on our home planet?

25Today, we are taking you on a tour of plasma.

26What it is, and where we can find it.

27But before we get out in the expanses of space, we have to start really, really small.

28Don Gurnett, University of Ohio Department of Physics and Astronomy, where I've worked for something close to 65 years.

29I've been other places in between, though.

30Don Gurnett has spent his career studying plasmas and plasma physics.

31To begin talking about plasmas, you have to start with a gas.

32And to turn that gas into a plasma, we've got to add a little bit of energy.

33On Earth's surface, we don't have any significant amount of plasma.

34We have neutral gas, thankfully, because plasma would probably cause you health problems.

35Like all states of matter, a plasma is made up of atoms or molecules that have been excited with energy.

36Those atoms are made up of three different particles.

37In a neutral state, an atom or molecule has the same number of positively charged protons as negatively charged electrons.

38If you could strip the electron off of the atom so that the electrons are free, then you have electrons and positive ions.

39That's called a plasma.

40So you might ask the question, how do you strip the electron off of the atom?

41And there's at least two ways that I'll mention.

42One is to heat the gas up to a very high temperature, so high that the vibration of the molecules will break off an electron.

43And that happens when you get an ordinary gas to a high temperature, like in a flame.

44If you get up to like 1,500 or 2,000 degrees, there'll be a bit of a plasma there.

45Under more extreme circumstances, like an electric arc welder, you know, which makes a big spark.

46Well, that's a plasma, actually.

47While most plasma is found out in space, there are a few instances where you can find it right here on Earth.

48Some of them you probably see every day.

49And others are more of a rare occurrence.

50On a daily basis, you can find plasma in fluorescent light bulbs, plasma screen TVs, and neon signs.

51But these are pretty small and contained cases.

52We don't start to see bigger instances of plasma until we head up into the Earth's atmosphere.

53When a lightning discharge occurs, you know, you see that flash across the sky.

54Well, that flash is caused by an electrical current, which heats the ordinary gas up to a very high temperature and makes a plasma calm, which is glows.

55And that's what you see is the lightning flash.

56That example tells you another important thing about a plasma compared to an ordinary neutral gas.

57A plasma conducts electricity.

58And that's what makes a plasma really different from an ordinary gas.

59It involves electricity and magnetism effects.

60It might be hard to conceptualize a plasma because we don't interact with them very often compared to a solid, liquid, or gas.

61But a plasma is very similar to a gas until you start looking at the magnetic or electric principles.

62This can make for some pretty strange effects and some pretty complicated science.

63Electric and magnetic fields are all around us.

64But they don't typically affect solids, liquids, and gases we interact with.

65They do shape plasma.

66And the further we start to get away from Earth's relatively neutral surface, the more often we can find these electrically charged gases.

67Hi, I'm Doug Roland, and I'm a scientist studying the Earth's upper atmosphere.

68And 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.

69Doug studies the layers of gases in our Earth's atmosphere as we move out towards space.

70So 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.

71And it's different during the day and at night.

72During the day, there'd be plasma at those altitudes.

73And that's generated as the sunlight shines on that gas.

74It's a very tenuous gas.

75So the sunlight shines on, the ultraviolet light breaks those atoms apart.

76At night, there's no sunlight.

77So depending on where you are in the world, there's no other source of ionization.

78So at night, you wouldn't see plasma that way.

79One of the reasons plasma doesn't last long here on Earth is because those atoms generally stay in their neutral form.

80And ions and electrons quickly come back together if they have been separated.

81However, 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.

82As you go up in altitude, the plasma can last for longer.

83So 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.

84So even after that part of the Earth's atmosphere rotates into the night side, you can persist for a long time.

85There's another way plasmas can be formed, besides separating atoms or molecules, and that's by adding extra electrons to a neutral gas.

86You can also create plasma by slamming into them with other particles like electrons.

87And the way the aurora created is you get electrons coming in from outer space, and they get shot down out of outer space into the atmosphere.

88The aurora, which you might know as the northern lights or southern lights, are beautiful displays of light in the night sky.

89These shifting sheets of light and color in our Earth's atmosphere appear mostly near the north and south poles.

90They 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.

91And when they do that, they run into gas molecules, gas atoms depending on what it is, and they can do two things.

92They can excite those atoms or molecules and make them emit light, like red light or green light like you might see in the aurora.

93And they can also sometimes break those atoms or molecules apart and make ions and electrons.

94The beautiful aurora are a visual side effect of some of the particles in Earth's atmosphere turning from a neutral gas into a plasma.

95But seeing the aurora isn't the only way we can experience a plasma.

96I have gotten into kind of an unusual area of research, and that is to study waves in plasma.

97Again, this is Professor Don Gurnett.

98You see, I'm talking here sound waves.

99That's the way I'm speaking.

100Plasma also has, it turns out, a wide variety of waves that can propagate in a plasma.

101We call them plasma waves.

102Since his time as an undergraduate at the University of Iowa, Don has been studying all the different ways we can hear plasma.

103And way back in, like, 1961, we had a visitor come here and play some unusual sounds that they detected on the ground.

104Things called whistlers.

105And I got very interested in this, and I decided to build just down in the basement of the physics building, just for fun.

106I 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.

107I couldn't use it around the city because the city has so much 60 hertz power line noise.

108So I took my receiver out to my father's farm, and we turned all the electricity off.

109And at first, I remember I was disappointed because I didn't hear anything but just kind of a hissy noise, which is the noise of the receiver.

110But then, I think it was on the third night, I heard very distinctly, I can't mimic that very well, but that's what it sounded like.

111So this was really exciting, not only to me, but a lot of people.

112And there are a lot of different things we can hear once we pick up sounds of plasma waves, including whistlers, hisses, and choruses.

113This is a whistler wave.

114Sounds pretty spacey, right?

115If you've got the right antenna out, you can hear those around lightning strikes.

116A chorus wave.

117Happens when loose electrons hit a plasma.

118And a hiss?

119Well, we're not yet sure what exactly causes a hiss, but it could be similar to a whistler wave or a chorus wave.

120Analyzing sounds can help scientists better understand the different ways plasma behaves.

121There's still a lot to learn about this mysterious substance, especially when you think about how much there is out in the observable universe.

122So it turns out that almost everything in our universe above an atmosphere altitude of about 100 kilometers is a plasma.

123Some people estimate that 99.9% of everything in the universe is a plasma.

124As we continue out on our plasma journey, the most significant source of plasma in our solar system is the sun.

125The sun is very hot, and it's a plasma.

126Stars, like our sun, are made of very hot gases.

127The sun is so hot that most of its gas has been ionized into a plasma.

128When those plasma particles leave the sun and head out in all directions into space, we call that solar wind.

129And we now know that every planet in our solar system encounters some of that plasma.

130We must talk about Voyager.

131In the late summer of 1977, two unmanned spacecraft, Voyager 1 and 2, lifted off from Cape Canaveral atop Titan-Centaur rockets.

132The 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.

133Traveling uninterrupted through interstellar space, the Voyagers will endure forever, long after everything man has ever built has crumbled into dust.

134The Voyagers journeyed to the furthest planets in our solar system.

135They 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 spaces between the stars.

136Well, we flew by with Voyager with a plasma wave instrument for the first time.

137We flew by Jupiter, Saturn, Uranus, and Neptune with Voyager 2.

138Voyager 1 only went to Jupiter and Saturn.

139At those flybys, we detected many of the same things that we detected at Earth.

140That was the first evidence of lightning at a planet other than Earth.

141So we now know that plasmas can be found in Earth's atmosphere, the sun, and the lightning strikes of other planets.

142But where is this 99.9% figure coming from?

143You 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.

144Most of interstellar space, the space between solar systems, is full of hydrogen and helium plasmas.

145These interstellar plasmas are the result of exploded giant stars millions of years ago.

146Overall, plasmas make up more matter than all of the solids, liquids, and gases in our universe combined.

147It'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.

148Here on Earth, we're surrounded by solids, liquids, and gases.

149And on a much larger scale, we're actually surrounded by plasmas.

150Our journey through this fascinating fourth state of matter started at some of the smallest particles and ends with the vastest distances in our universe.

151And isn't it wonderful that there's still so much to learn?

152This is NASA's Curious Universe.

153This episode was written and produced by Christina Dana.

154Our executive producer is Katie Atkinson.

155The Curious Universe team includes Maddie Arnold, Kate Steiner, and Michaela Sosby, with support from Emma Edmond and Priya Mittal.

156Our theme song was composed by Matt Russo and Andrew Santaguida of System Sounds.

157Special thanks to Kala Cofield, Sarah Frazier, Miles Hatfield, Ryland Hegey, Joy Eng, Nick Tomlanovic, Lena Tran, and the Heliophysics team.

158If you liked this episode, please let us know by leaving us a review, tweeting about the show at NASA, and sharing NASA's Curious Universe with a friend.

159Learn more about plasma and heliophysics by visiting science.nasa.gov slash heliophysics.

160Still curious about NASA?

161You can send us questions about this episode or a previous one, and we'll try to track down the answers.

162You can email a voice recording or send a written note to nasa-curiousuniverse at mail.nasa.gov.

163Go to nasa.gov slash curiousuniverse for more information.

164Well, my dad was an engineer back in the day, and he was always building things.

165They were kind of very concrete things.

166Like we built a TV antenna for our house.

167We'd get television back in the day before cable.

168We built things like that.

169And when I went to college, I said, well, I'm going to do something technical.

170I wasn't sure.

171I heard that a summer internship program was opening up for a team that was doing balloon research.

172And this was a group that was doing astronomy.

173I said, astronomy?

174What does that have to do with balloons?

175And 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.

176And they flew it on this gigantic balloons out of Fort Sumner, New Mexico.

177And they needed a roadie.

178And I said, I'm going to be the roadie.

179I'm going to go along and drive the truck, basically, for them and carry all their stuff.

180It was really fun because you got to see like kind of a small group of people who were really dedicated, really excited about something, working really closely together at a high level of performance and just having that camaraderie.

181So it was really the people that attracted me, not the science per se.

182who were really excited about it.

183And I said, I'm going to be the people who were really excited about it.

184who were really excited about it.

185I'm going to be the people who were really excited about it.

186And I said, And I said,