The Star in Our Backyard

01We're very used to the sun.

02It's our star.

03We see it in the sky every day.

04We know that it has a lot of impact of what happens to us here on Earth.

05But of course, it's even more than that.

06The sun actually shapes our entire neighborhood as we orbit around the Milky Way.

07Understanding the sun and how it works is very, very fundamental to us.

08This is NASA's Curious Universe.

09Our universe is a wild and wonderful place.

10I'm Patti Boyd, and in this podcast, NASA is your tour guide.

11This week's adventure takes us to the very center of our solar system.

12We're visiting our neighborhood star, the sun.

13For me, what makes the sun really cool is it's kind of like having a star in your backyard.

14Hi, I am Nikki Fox, and I am the director of NASA's Heliophysics Division.

15You know, we're used to looking up at night and seeing all the beautiful stars, beautiful constellations, planets glowing, and it's all wonderful.

16And then you realize the sun is just like an average star, but it's very close to us.

17And so, number one, it means that we can study it in very, very, very detailed ways.

18But also, because we live so close to it, we kind of live in the atmosphere of the sun.

19If we can understand our star, then it helps us understand stars in other solar systems or stellar systems.

20So everything's happening in heliophysics.

21The sun is responsible for life as we know it.

22Its gravity holds the solar system together, keeping everything from the biggest planets to the smallest particles of debris in its orbit.

23But it also drives a vast space weather system of particles that weave through space.

24That's what NASA's Heliophysics Division studies.

25The sun's outer atmosphere actually moves all the way out through the edge of our solar system.

26That's actually what's creating this boundary.

27And so we live in the atmosphere of the sun.

28So when the sun is a very, very active star, that actually drives what we see here at Earth.

29Earth is orbiting through a space soup of solar particles.

30The interactions between the sun and Earth create a complex space environment.

31It drives effects from the beautiful to the detrimental.

32It creates aurora, but it also interferes with satellite electronics or GPS signals.

33That soup of particles also protects us.

34It extends billions of miles out, far past the last planets.

35And we wouldn't be here today without it.

36The sun creates this protective bubble that really protects us from all of the vagaries of interstellar space.

37So 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.

38The sun is very dynamic.

39It's an exciting field to be in because the sun changes every day.

40So you always have something new to study.

41But for me, the big attraction about studying the sun is it's studying a star.

42And right now, it's the only star that we can study up close.

43The sun is our closest star.

44It's our protector, our life giver.

45And it's also our only close-up and personal glimpse into star science overall.

46Though we see the sun daily, there's a lot that would surprise you.

47I think a lot of people look at the sun and just think it's a bright, you know, ball of light.

48Or some people think it's a bright ball of fire in the sky.

49But the sun is very complicated.

50Our star is actually a hot ball of glowing, electrically charged gas.

51And it's made up of many different layers.

52Let's break them down.

53Our star has a core.

54It's not solid, and it works kind of like a nuclear reactor.

55Nuclear fusion happens there, producing all of the energy that eventually makes it out of the sun as light and radiation.

56After that comes the radiative zone.

57It's the region where things literally radiate out of the core.

58Then there's the convective zone, where the sun begins to act a bit like boiling water.

59Then there is the kind of visible, what we think of as the visible surface.

60We call it the photosphere.

61It's not an actual surface.

62It's not solid.

63But it's what our eyes see as the kind of outermost region of the sun.

64However, there are two more layers.

65It's just we can't see them because this visible surface is so bright that you can't see those hazy layers.

66These layers are the chromosphere and the corona.

67We can't see them because the visible light is so bright, making these layers seem hazy.

68The corona in particular is especially crucial.

69The 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.

70That'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.

71So the sun is a lot more complicated than you might think by just looking at it from here at Earth.

72That solar atmosphere, the corona, that's what's driving all the changes in space throughout the solar system.

73While the corona affects us the most, it's still the most mystifying part of our sun.

74The corona, it is extremely hot.

75It's on average 2 million degrees.

76That's Aleda Higginson.

77She's a heliophysicist at the Johns Hopkins University Applied Physics Lab.

78The weird part is that it's actually hotter than the surface of the sun.

79So colloquially, we all talk about how, oh yeah, the surface of the sun, like that's some really hot, big number.

80And it is.

816,000 degrees is really hot.

82But then you multiply that and that is what the atmosphere of the sun actually, how hot it actually is.

83So that is something that we just, you cannot have a physical grasp on as a human.

84The corona's high temperatures are a bit of a mystery to scientists.

85As you move away from the surface of the sun, the temperatures actually get hotter.

86Imagine sitting next to a campfire, but then feeling warmer as you walk away.

87It may sound strange, but this is exactly what seems to happen in the sun.

88The sun is incredibly violent.

89It's aggressive.

90It's aggressive.

91So if you could fly next to the sun, you would be blinded by the amount of light that it's putting out.

92You actually probably wouldn't if you could magically survive in a vacuum.

93You 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.

94So the front of you would be really hot and the back of you would be really cold.

95Because even though we have all that material in space next to the sun surrounding the sun, it's not very dense.

96Our star is not a burning ball of fire.

97It's plasma.

98A soupy mixture of electrically charged gases, mostly hydrogen and helium.

99The sun is made of 90% plasma.

100Its unique makeup means that the laws of gravity, the force we experience most on Earth, is only one of the forces driving how particles move.

101So all that plasma moves around unlike anything we have normally experienced on Earth.

102Our sun is an active star.

103It releases a constant stream of that solar material, the plasma, in all directions, at all times.

104Our star's activity creates what we call space weather.

105Space weather is the term that we use to define all of the dynamic activity.

106The sun's activity makes its way through space and then impacts the Earth system.

107NASA cares a lot about understanding space weather because it can be very disruptive.

108It can trigger power outages and disrupt GPS signals.

109It can also affect astronauts and spacecraft in space.

110It also can change in a really large way really suddenly.

111So you can have several days of just kind of background low-level variation in the space weather activity.

112And then suddenly there'll be a huge eruption on the surface of the sun.

113And then that can, within a matter of minutes, cause all kinds of interference here at Earth just from the radiation from the sun.

114The sun impacts us here on Earth.

115And it's also a laboratory for understanding the stars far beyond our solar system.

116Scientists like Nikki and Aleda are working to unravel the mysteries of our star.

117There are a couple of mysteries we've known about for, you know, well over 100 years.

118The corona, this hazy atmosphere, it's hotter than the surface of the sun by about 300 times.

119And that doesn't make sense.

120We call it the coronal heating mystery.

121What is it that's happening that's actually causing this heating?

122And we've known about these questions.

123But, you know, you can study the sun from all different kinds of wavelengths, which we have done.

124We've sent spacecraft in as far as the planet Mercury.

125And we've done amazing science.

126But we've never really been able to go and visit exactly where this heating is happening.

127In 2018, NASA launched a mission to touch the sun.

1283, 2, 1, 0.

129Liftoff of the mighty Delta IV heavy rocket with NASA's Parker Solar Probe.

130Parker Solar Probe.

131A mission headed to explore the unknown.

132It's on a voyage of discovery.

133And it's looking for some answers to those big questions.

134Parker Solar Probe is actually flying in to the sun's corona, making cuts through the sun's corona, very close to the sun.

135And is already returning amazing data to us.

136It's getting closer to the sun than humankind has ever sent a probe before.

137And it's actually going to be touching the very outer layers where the corona transitions to the solar wind.

138And studying the mysteries that are there and trying to understand why is the corona so hot?

139Why is the sun's atmosphere so hot?

140We think we know where the energy is coming from.

141But we just don't know how it's getting there.

142So that is something that we're hoping Parker Solar Probe will be able to shed light on.

143And is one of the biggest questions that will probably have some important implications for physics in general as well.

144Not just for space weather and the sun.

145There's a lot to study with heliophysics.

146There's many, many different aspects of it that you can study.

147And it's a great time to be a heliophysicist.

148We're launching great missions to all these key locations.

149Some people say, you know, it's a new discipline of science.

150I would say it's the original discipline of science.

151Everybody looked up at the sun at some point and wondered what it was and how it affected us.

152And that's what we study in heliophysics.

153There are billions of stars like ours scattered throughout the Milky Way.

154But the sun is incredibly important to us.

155It's ours.

156And it affects so much of what we experience here on Earth.

157We still have plenty of questions about the star in our backyard.

158With each day, NASA's sun scientists gain a new understanding of it.

159And get a little closer to unraveling its mysteries.

160This is NASA's Curious Universe.

161The Curious Universe team includes Elizabeth Tamme and Michaela Sosby.

162Our executive producer is Katie Atkinson.

163Special thanks to Karen Fox, Sarah Frazier, and the Johns Hopkins University Applied Physics Lab.

164If you liked this episode, please let us know by leaving a review, tweeting about it at NASA, and sharing it with a friend.

165You can also tag along on more solar adventures by following at NASA's sun on social media.

166Thank you for listening to NASA's Curious Universe.

167Our universe is a wild and wonderful place, and we've enjoyed exploring it with you.

168We're taking a break now, but we'll be back before you know it.

169Until then, you can continue exploring the universe and discovering our home planet with NASA by visiting nasa.gov.

170You can also follow NASA on Twitter, Instagram, and Facebook.

171And find more NASA podcasts in your app or at nasa.gov slash podcasts.

172NASA's Curious Universe