WEBVTT - How Does the Sun Rotate?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff Lauren Vobebaum. Here.

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<v Speaker 1>Back in the sixteen hundreds, astronomer Galileo Galilei peered into

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<v Speaker 1>his telescope and discovered dark spots on the Sun. He

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<v Speaker 1>subsequently noticed that they seemed to move, vanishing and then returning.

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<v Speaker 1>He wrote in sixteen thirteen, it is also manifest that

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<v Speaker 1>their rotation is about the Sun, and though he noted

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<v Speaker 1>it was possible that the sun spots were moving while

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<v Speaker 1>the Sun stayed in place, he continued to me, it

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<v Speaker 1>seems more probable that the movement is of the solar

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<v Speaker 1>globe than of its surroundings. Galileo had discovered that the Sun,

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<v Speaker 1>like numerous other celestial objects, rotates on an axis, but

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<v Speaker 1>the length of time and manner in which the Sun

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<v Speaker 1>rotates is different than that of a rocky planet such

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<v Speaker 1>as Earth. That second difference actually causes the Sun spots

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<v Speaker 1>that originally led to Galileo's discovery. For the article, this

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<v Speaker 1>episode is based on How Stuff Works. Spoke with Clear Raptory,

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<v Speaker 1>a head of Education and Outreach for the National Solar Observatory,

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<v Speaker 1>the US Center for Ground Based Solar Physics. She said

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<v Speaker 1>pretty much, everything in the universe rotates, everything is moving

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<v Speaker 1>relative to everything else. That is a direct explanation that's

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<v Speaker 1>accurate and also opened a lot of questions for me. Okay,

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<v Speaker 1>researchers think that everything in the universe is moving and

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<v Speaker 1>rotating because they're all exerting gravity on each other. You know,

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<v Speaker 1>everything's pulling on everything else a little. And because the

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<v Speaker 1>universe was born with some amount of angular momentum or

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<v Speaker 1>rotational movement or spin, and angular momentum is a physical

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<v Speaker 1>property that is conserved. Let's unpack that a little. You've

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<v Speaker 1>probably encountered Newton's laws of motion, the first of which

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<v Speaker 1>is that an object in linear motion will stay in

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<v Speaker 1>motion unless something MUCKs around with it, and the same

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<v Speaker 1>basic rule applies to angular momentum. Left to its own devices,

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<v Speaker 1>an object that's spinning is going to keep spinning. These

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<v Speaker 1>rules are the conservation of momentum. So basically, the Sun

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<v Speaker 1>rotates on its axis now because everything in the galaxy

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<v Speaker 1>is rotating around the galaxy center. That includes the clouds

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<v Speaker 1>of dust and hydrogen gas that the Sun condensed from

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<v Speaker 1>billions of years ago. Those clouds were also whirling vaguely

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<v Speaker 1>around day shifting central point. But as the proto Sun

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<v Speaker 1>gradually gathered mass and developed the gravity that attracted more

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<v Speaker 1>and more nearby molecules to it, it also conserved that

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<v Speaker 1>angular momentum or spin, and in the same way that

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<v Speaker 1>a figure skater can spin faster by tucking their arms

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<v Speaker 1>in towards their body, the Sun went from a lazy

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<v Speaker 1>whirl to a relatively quick spin as it gathered mass.

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<v Speaker 1>The Sun's general rotation isn't difficult to measure because the

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<v Speaker 1>thin visible solar surface called the photosphere has visible features

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<v Speaker 1>like sun spots and prominences, some of which last long

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<v Speaker 1>enough that they can be observed as they move around,

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<v Speaker 1>just as Galileo did. But from there it gets a

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<v Speaker 1>little complicated. Remember that the Sun is made up of

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<v Speaker 1>plasma that is a super hot, electrically charged gas rafter

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<v Speaker 1>he said, It's not a solid body, so it doesn't

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<v Speaker 1>rotate as a single solid ball. Instead, the gas rotates

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<v Speaker 1>more rapidly at the equator than at the poles. A

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<v Speaker 1>spot at the equator goes around in just about twenty

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<v Speaker 1>four Earth day, while the polar regions take six whole

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<v Speaker 1>days longer or more. This is more similar to how

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<v Speaker 1>Jupiter and the other gas giant planets rotate than the

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<v Speaker 1>way that Earth or Mars rotates, and this differential rotation

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<v Speaker 1>is actually what causes sunspots and some other strange and

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<v Speaker 1>interesting features of the Sun. The Sun's magnetic field, which

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<v Speaker 1>is generated just below the surface, basically gets wrapped around

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<v Speaker 1>itself by this uneven motion. The result is development of

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<v Speaker 1>high density magnetic bands that eventually burst through the surface,

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<v Speaker 1>causing the eruptions that we see as sunspots and flares.

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<v Speaker 1>They appear in a regular eleven year cycle called the

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<v Speaker 1>solar cycle, during which the number of sunspots increases and

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<v Speaker 1>then decreases again. Beneath the photosphere lies the convection zone,

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<v Speaker 1>a thick layer where currents of plasma form. It rotates

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<v Speaker 1>roughly the same is the surface, but deeper inside the Sun.

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<v Speaker 1>Scientists aren't sure whether other parts, like the radiative zone

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<v Speaker 1>and the core, move at different rates. A Raftery said,

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<v Speaker 1>we have some good ideas about this, but it's still

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<v Speaker 1>an active question. Because scientists can't look into the Sun

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<v Speaker 1>beneath the photosphere, they instead study how it sounds. A

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<v Speaker 1>Raftery explained, the inside of the Sun acts almost like

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<v Speaker 1>a bell. There are sound waves bouncing around inside. To

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<v Speaker 1>measure these sound waves, the National Solar Observatory uses data

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<v Speaker 1>collected by its Global Oscillation Network Group or GONG, which

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<v Speaker 1>is an array of telescopes and other instruments at six

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<v Speaker 1>different locations around the world, and uses sophisticated mathematics to

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<v Speaker 1>discern solar vibrations. So will the Sun keep spinning forever? Yep?

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<v Speaker 1>Basically due to the aforemanvation of angular momentum. About five

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<v Speaker 1>billion years from now, the Sun will begin to run

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<v Speaker 1>out of fuel and expand into a red dwarf star,

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<v Speaker 1>then will collapse into a compact white dwarf and eventually

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<v Speaker 1>a dense stellar crystal. But even then it will continue

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<v Speaker 1>to rotate, though at different speeds, because pretty much everything

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<v Speaker 1>is rotating and always has been. Today's episode is based

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<v Speaker 1>on the article does the Sun Rotate? On how Stuffworks

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<v Speaker 1>dot Com? Written by Patrick J. Higer. Brain Stuff is

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<v Speaker 1>production by Heart Radio in partnership with how Stuffworks dot Com,

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<v Speaker 1>and it is produced by Tyler Klang. Four more podcasts

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<v Speaker 1>my heart Radio, visit the Aheartradio app, Apple Podcasts, or

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