Speaker 1: Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff Lauren Vobebaum. Here.
Speaker 1: Back in the sixteen hundreds, astronomer Galileo Galilei peered into
Speaker 1: his telescope and discovered dark spots on the Sun. He
Speaker 1: subsequently noticed that they seemed to move, vanishing and then returning.
Speaker 1: He wrote in sixteen thirteen, it is also manifest that
Speaker 1: their rotation is about the Sun, and though he noted
Speaker 1: it was possible that the sun spots were moving while
Speaker 1: the Sun stayed in place, he continued to me, it
Speaker 1: seems more probable that the movement is of the solar
Speaker 1: globe than of its surroundings. Galileo had discovered that the Sun,
Speaker 1: like numerous other celestial objects, rotates on an axis, but
Speaker 1: the length of time and manner in which the Sun
Speaker 1: rotates is different than that of a rocky planet such
Speaker 1: as Earth. That second difference actually causes the Sun spots
Speaker 1: that originally led to Galileo's discovery. For the article, this
Speaker 1: episode is based on How Stuff Works. Spoke with Clear Raptory,
Speaker 1: a head of Education and Outreach for the National Solar Observatory,
Speaker 1: the US Center for Ground Based Solar Physics. She said
Speaker 1: pretty much, everything in the universe rotates, everything is moving
Speaker 1: relative to everything else. That is a direct explanation that's
Speaker 1: accurate and also opened a lot of questions for me. Okay,
Speaker 1: researchers think that everything in the universe is moving and
Speaker 1: rotating because they're all exerting gravity on each other. You know,
Speaker 1: everything's pulling on everything else a little. And because the
Speaker 1: universe was born with some amount of angular momentum or
Speaker 1: rotational movement or spin, and angular momentum is a physical
Speaker 1: property that is conserved. Let's unpack that a little. You've
Speaker 1: probably encountered Newton's laws of motion, the first of which
Speaker 1: is that an object in linear motion will stay in
Speaker 1: motion unless something MUCKs around with it, and the same
Speaker 1: basic rule applies to angular momentum. Left to its own devices,
Speaker 1: an object that's spinning is going to keep spinning. These
Speaker 1: rules are the conservation of momentum. So basically, the Sun
Speaker 1: rotates on its axis now because everything in the galaxy
Speaker 1: is rotating around the galaxy center. That includes the clouds
Speaker 1: of dust and hydrogen gas that the Sun condensed from
Speaker 1: billions of years ago. Those clouds were also whirling vaguely
Speaker 1: around day shifting central point. But as the proto Sun
Speaker 1: gradually gathered mass and developed the gravity that attracted more
Speaker 1: and more nearby molecules to it, it also conserved that
Speaker 1: angular momentum or spin, and in the same way that
Speaker 1: a figure skater can spin faster by tucking their arms
Speaker 1: in towards their body, the Sun went from a lazy
Speaker 1: whirl to a relatively quick spin as it gathered mass.
Speaker 1: The Sun's general rotation isn't difficult to measure because the
Speaker 1: thin visible solar surface called the photosphere has visible features
Speaker 1: like sun spots and prominences, some of which last long
Speaker 1: enough that they can be observed as they move around,
Speaker 1: just as Galileo did. But from there it gets a
Speaker 1: little complicated. Remember that the Sun is made up of
Speaker 1: plasma that is a super hot, electrically charged gas rafter
Speaker 1: he said, It's not a solid body, so it doesn't
Speaker 1: rotate as a single solid ball. Instead, the gas rotates
Speaker 1: more rapidly at the equator than at the poles. A
Speaker 1: spot at the equator goes around in just about twenty
Speaker 1: four Earth day, while the polar regions take six whole
Speaker 1: days longer or more. This is more similar to how
Speaker 1: Jupiter and the other gas giant planets rotate than the
Speaker 1: way that Earth or Mars rotates, and this differential rotation
Speaker 1: is actually what causes sunspots and some other strange and
Speaker 1: interesting features of the Sun. The Sun's magnetic field, which
Speaker 1: is generated just below the surface, basically gets wrapped around
Speaker 1: itself by this uneven motion. The result is development of
Speaker 1: high density magnetic bands that eventually burst through the surface,
Speaker 1: causing the eruptions that we see as sunspots and flares.
Speaker 1: They appear in a regular eleven year cycle called the
Speaker 1: solar cycle, during which the number of sunspots increases and
Speaker 1: then decreases again. Beneath the photosphere lies the convection zone,
Speaker 1: a thick layer where currents of plasma form. It rotates
Speaker 1: roughly the same is the surface, but deeper inside the Sun.
Speaker 1: Scientists aren't sure whether other parts, like the radiative zone
Speaker 1: and the core, move at different rates. A Raftery said,
Speaker 1: we have some good ideas about this, but it's still
Speaker 1: an active question. Because scientists can't look into the Sun
Speaker 1: beneath the photosphere, they instead study how it sounds. A
Speaker 1: Raftery explained, the inside of the Sun acts almost like
Speaker 1: a bell. There are sound waves bouncing around inside. To
Speaker 1: measure these sound waves, the National Solar Observatory uses data
Speaker 1: collected by its Global Oscillation Network Group or GONG, which
Speaker 1: is an array of telescopes and other instruments at six
Speaker 1: different locations around the world, and uses sophisticated mathematics to
Speaker 1: discern solar vibrations. So will the Sun keep spinning forever? Yep?
Speaker 1: Basically due to the aforemanvation of angular momentum. About five
Speaker 1: billion years from now, the Sun will begin to run
Speaker 1: out of fuel and expand into a red dwarf star,
Speaker 1: then will collapse into a compact white dwarf and eventually
Speaker 1: a dense stellar crystal. But even then it will continue
Speaker 1: to rotate, though at different speeds, because pretty much everything
Speaker 1: is rotating and always has been. Today's episode is based
Speaker 1: on the article does the Sun Rotate? On how Stuffworks
Speaker 1: dot Com? Written by Patrick J. Higer. Brain Stuff is
Speaker 1: production by Heart Radio in partnership with how Stuffworks dot Com,
Speaker 1: and it is produced by Tyler Klang. Four more podcasts
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