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. Visit the Amazon rainforest, explore faraway galaxies and dive into our astronaut training pool. First-time space explorers welcome.

About the Episode

Our Sun holds the solar system together and is responsible for life as we know it. Though it may seem calm and unchanging, the Sun is dynamic. Join NASA solar scientists on a trip around the Sun, our lively and mysterious neighborhood star.

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[MUSIC: FLOATING MOLECULES]

NICKY FOX: We’re very used to the Sun… It’s our star. We see it in the sky every day. We know that it has a lot of impact on what happens to us here on Earth, but of course, it’s even more than that… The Sun actually shapes our entire neighborhood as we orbit around the Milky Way.

NICKY FOX: Understanding the Sun and how it works is very, very fundamental to us…

PADI BOYD HOST: T his 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.

PADI BOYD HOST: This week’s adventure takes us to the very center of our solar system. We’re visiting our neighborhood star… the Sun.

[SONG FADES OUT SLOWLY]

[PAUSE/MUSIC SHIFT PARADIGM BY DURY]

NICKY FOX: So, for me what makes the Sun really cool is It’s like having a star in your backyard.

NICKY FOX: Hi, I’m Nicky Fox and I’m the director of NASA’s Heliophysics Division.

NICKY FOX: You know, we’re used to looking up at night and seeing all the beautiful stars, beautiful constellations, planets glowing, and it’s all wonderful, and then you realize the Sun is just like an average star but it’s very close to us. So, number one, it means we can study it in very detailed ways… but also, because we live so close to it, we live in the atmosphere of the Sun. If we can understand our star, it helps us understand other stars. So, everything is happening in Heliophysics!

HOST PADI BOYD: The Sun is responsible for life as we know it. Its gravity holds the solar system together, keeping everything – from the biggest planets to the smallest particles of debris – in its orbit.

HOST PADI BOYD: But it also drives a vast space weather system of particles that weave throughout space – and that’s what NASA’s Heliophysics division studies.

NICKY FOX: Because we live so close to it, we kind of live in the atmosphere of the Sun. The Sun’s outer atmosphere moves all the way out through the edge of our solar system. And so we live in the atmosphere of the Sun. So when the Sun is a very, very active star, that actually drives what we see here on Earth.

HOST PADI BOYD: Our Earth is orbiting through a space soup of solar particles. tThe interactions between the Sun and Earth create a complex space environment. It drives effects from the beautiful to the detrimental. It creates the aurora, but it also interferes with satellite electronics or GPS signals.

HOST PADI BOYD: That soup of particles also protects us. It extends billions of miles out – far past the last planets – and we wouldn’t be here today without it.

NICKY FOX: The Sun creates this protective bubble that really protects from all of the vagaries of interstellar space, so all the nasty things that are outside are kind of kept at bay by this atmosphere and this boundary that the Sun creates for us.

NICKY FOX: The Sun is very dynamic and it’s an exciting field to be in because the Sun changes every day. It’s, you always have something new to study, but for me the big attraction about studying the Sun is it’s studying a star. And right now, it’s the only star that we can study up close.

HOST PADI BOYD: The Sun is our closest star. It’s our protector, our life-giver. . . . And it’s also our only up-close and personal glimpse into star science overall.

HOST PADI BOYD: Though we see the Sun daily, there’s a lot that would surprise you.

NICKY FOX: I think a lot of people look at the Sun and just think it’s a bright ball of light, or some people think it’s a bright ball of fire in the sky. But the Sun is very complicated.

HOST PADI BOYD: Our star is actually a hot ball of glowing, electrically-charged gas… and it’s made up of many different layers. Let’s break them down. Our star has a core. It’s not solid, and it works kind of like a nuclear reactor. Nuclear fusion happens there, producing all of the energy that eventually makes it out of the sun as light and radiation.

HOST PADI BOYD: After that comes the radiative zone. It’s the region where things literally radiate out of the core. Then, there’s the convective zone, where the Sun begins to act a bit like boiling water.

NICKY FOX: Then there is the kind of visible, what we think of as the visible surface. We call it the photosphere. It’s not an actual surface, it’s not solid, but it’s what our eyes see as the kind of outermost region of the Sun. However, there are two more layers. It’s just we can’t see them because this visible surface is so bright that you can’t see those hazy layers…

HOST PADI BOYD: These layers are the chromosphere and the corona. We can’t see them because the visible light is so bright, making these layers seem hazy. The corona, in particular, is especially crucial.

NICKY FOX: The most important thing for us here at Earth is the corona, which is that bright, hazy atmosphere that you see during a total solar eclipse. That’s the only time you can see it because finally the Moon blocks out that bright point of light that we see, and you can see that beautiful corona around it. So the Sun is a lot more complicated than you might think by just looking at it from here at Earth.

HOST PADI BOYD: That solar atmosphere, the corona – that’s what’s driving all the changes in space weather throughout the solar system. While the corona affects us the most, it’s still the most mystifying part of our Sun.

ALEIDA HIGGINSON: The corona, it is extremely hot . It’s on, on average 2 million degrees.

HOST PADI BOYD: That’s Aleida Higginson. She’s a heliophysicist at The Johns Hopkins University Applied Physics Lab.

ALEIDA HIGGINSON: The weird part is that it’s actually hotter than the surface of the Sun. So, colloquially, we all talk about how, Oh yeah, the surface of the Sun, like, like that’s some really hot, hot, big number and it is 6,000 degrees, it’s really hot… but then you multiply that, and that is what the atmosphere of the Sun actually is. So, that is something that we just, you cannot have a physical grasp on as a human.

HOST PADI BOYD: The corona’s high temperatures are a bit of a mystery to scientists. As you move away from the surface of the Sun, the temperatures actually get hotter. Imagine sitting next to a campfire, but then feeling warmer as you walk away. It may sound strange, but this is exactly what seems to happen in the Sun. And heliophysicists have been trying to solve this mystery for a long time.

[MUSIC: NATURAL TIME CYCLES]

ALEIDA HIGGINSON: The Sun is incredibly violent. It’s aggressive. So if you could fly next to the Sun, you would be blinded by the amount of light that it’s putting out. You actually probably wouldn’t, if you could magically, survive in a vacuum, you might not feel the heat from the material surrounding you as much as you would just feel the heat from the radiation of the Sun. So the front of you would be really hot on the back of you would be really cold because even though we have all that material in space next to the sun surrounding the Sun, it’s not very dense…

HOST PADI BOYD: Our star is not a burning ball of fire, It’s plasma… A soupy mixture of electrically-charged gases… mostly hydrogen and helium. The Sun is made of 90 percent plasma…Its unique makeup means that the laws of gravity – the force we experience most on Earth – is only one of the forces driving how the particles move. Soall that plasma moves around unlike anything we normally experience on Earth.

HOST PADI BOYD: Our Sun is an active star. It releases a constant stream of that solar material, the plasma, in all directions, at all times. Our star’s activity creates what we call space weather.

ALEIDA HIGGINSON: Space weather is the term that we use to define all of the dynamic activity that’s driven by, uh, the Sun’s activity and makes its way through space and then impacts the Earth system.

HOST PADI BOYD: NASA cares a lot about understanding space weather because it can be very disruptive! It can trigger power outages and disrupt GPS signals. It can also affect astronauts and spacecraft in space!

ALEIDA HIGGINSON: So you can have several days of just kind of background, low-level variation in the space of weather activity. And then suddenly there’ll be a huge eruption on the surface of the Sun. And then that can within a matter of minutes cause all kinds of interference here at Earth, just from the radiation from the Sun.

HOST PADI BOYD: The Sun impacts us here on Earth and it’s also a laboratory for understanding the stars far beyond our solar system. Scientists like Nicky and Aleida are working to unravel the mysteries of our star.

NICKY FOX:… So there are a couple of mysteries that we’ve known about for well over a hundred years. But just, why is the corona this hazy atmosphere, it’s hotter than the surface of the Sun by about 300 times. And that doesn’t make sense. We call it the “Coronal Heating Mystery.” What is it that’s happening that’s actually causing this heating?

HOST PADI BOYD: In 2018, NASA launched a mission to “touch the Sun.”

[MISSION LAUNCH AUDIO: 3…2…1…0. Liftoff of the mighty Delta IV Heavy rocket, with NASA’s Parker Solar Probe.]

HOST PADI BOYD: Parker Solar Probe, a mission headed to explore the unknown. It’s on a voyage of discovery… and it’s looking for some answers to those big questions.

NICKY FOX: Parker Solar Probe is actually flying into the Sun’s corona, making cuts through the Sun’s corona, very close to the Sun, and is already returning amazing data to us.

ALEIDA HIGGINSON: It’s getting closer to the Sun than humankind has ever sent a probe before. And it’s actually going to be touching the very outer layers where the corona transitions to the solar wind and studying the mysteries that are there and trying to understand why is the corona so hot? Why is the Sun’s atmosphere so hot? We think we know where the energy is coming, but we just don’t know how it’s getting there. So that is something that we’re hoping Parker Solar Probe will be able to shed light on and is one of the biggest questions that will probably have some important implications for physics in general as well, not just for space, weather and the Sun.

NICKY FOX: It’s a great time to be a heliophysicist. We’re launching great missions to all these key locations, and so, some people say you know, it’s a new discipline of science, I would say it’s the original discipline of science because everybody looked up at the Sun at some point and wondered what it was and how it affected us and that’s what we study in heliophysics.

[MUSICAL Transition]

HOST PADI BOYD: There are billions of Stars like ours scattered throughout the milky way, but the Sun is incredibly important to us. It’s ours! And it affects so much of what we experience here on Earth. We still have plenty of questions about the star in our backyard. With each day, NASA’s sun scientists gain a new understanding of it… and get a little closer to unraveling its mysteries.

[MUSICAL TRANSITION FADE OUT]

HOST PADI BOYD: This is NASA’s Curious Universe. The Curious Universe team includes Elizabeth Tammi and Micheala Sosby. Our executive producer is Katie Atkinson. Special thanks to Karen Fox, Sarah Frazier and The Johns Hopkins University Applied Physics Lab. If you enjoyed this episode, be sure to leave us a rating or review in your podcast app, sharing it with a friend or tweeting about the show @NASA. You can also tag along on more solar adventures by following @NASASun on social media.

HOST PADI BOYD: Thank you for listening to the first season of NASA’s Curious Universe. Our universe is a wild and wonderful place, and we’ve enjoyed exploring it with you! We’re taking a break now, but will be back before you know it. Until then, you can continue exploring the universe and discovering our home planet with NASA by visiting nasa.gov. You can also follow NASA on Twitter, Instagram and Facebook. And, find more NASA podcasts in your app or at nasa.gov/podcasts.