WEBVTT - BrainStuff Classics: What Makes Stars Twinkle?

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<v Speaker 1>Welcome to brain Stuff production of I Heart Radio. Hi

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<v Speaker 1>brain Stuff. I'm Lauren vogel Bom and this is another

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<v Speaker 1>classic episode. In this one, we dip into the everyday

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<v Speaker 1>science of why the stars and our skies, most of

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<v Speaker 1>which emit fairly constant light, appear to twinkle. Hey, brain Stuff,

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<v Speaker 1>Lauren Vogel bomb Here. All things considered, our atmosphere is

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<v Speaker 1>pretty great. This blanket of nitrogen, oxygen, and other gases

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<v Speaker 1>keeps the world's temperature nice and habitable while protecting us

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<v Speaker 1>from harmful U V radiation, to say nothing of this

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<v Speaker 1>space debris it vaporizes for us. Oh yeah, and without

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<v Speaker 1>all that oxygen in our atmosphere, animal life couldn't survive

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<v Speaker 1>on planet Earth. Not a bad resume. But despite its

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<v Speaker 1>many good qualities, the atmosphere can be a nuisance to

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<v Speaker 1>astronomy buffs. That's because it distorts light. At night, the

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<v Speaker 1>atmosphere makes some heavenly bodies appear to flicker and shimmer.

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<v Speaker 1>The technical term for this phenomenon is astronomical scintillation. You

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<v Speaker 1>probably know it by a different name, twinkling like an onion.

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<v Speaker 1>The atmosphere is made up of layers. At the bottom

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<v Speaker 1>is the troposphere, which starts right here at ground level

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<v Speaker 1>on the planet's surface, standing about five to nine miles

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<v Speaker 1>that's eight to four point five kilometers tall. It's where

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<v Speaker 1>most of Earth's weather events take place. The other layers

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<v Speaker 1>are in ascending order, the stratosphere, mesosphere, thermosphere, and exosphere.

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<v Speaker 1>There's also a region called the ionosphere, which encompasses parts

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<v Speaker 1>of both the mesosphere and the thermosphere. These layers have

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<v Speaker 1>different temperatures. In addition, the air's density varies from level

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<v Speaker 1>to level. When starlight enters our atmosphere, it runs into

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<v Speaker 1>pockets of cool and warm air. The pockets act as

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<v Speaker 1>big lenses, causing the light to change direction or refract

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<v Speaker 1>as it passes through them. Yet the lenses are not

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<v Speaker 1>fixed in place. They move around in a shape as

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<v Speaker 1>they shift. So does starlight refraction. That's why the stars

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<v Speaker 1>appear to twinkle. Scintillation affects planets to Mercury, Venus, Mars,

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<v Speaker 1>and the other planets in our Solar system do twinkle

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<v Speaker 1>when viewed from Earth on a clear night. So does

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<v Speaker 1>our moon. However, the planets twinkled to a barely noticeable

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<v Speaker 1>degree distance is the main reason stars twinkle. More conspicuously

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<v Speaker 1>than the planets in our Solar system. Because the former

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<v Speaker 1>are so far away, each star looks like a single

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<v Speaker 1>pinpoint of light, a single pixel. You might say. It's

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<v Speaker 1>a different story for Earth's moon and our neighboring planets,

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<v Speaker 1>being a lot closer, they are less affected by the atmosphere.

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<v Speaker 1>Planets and moons appear as tiny disks up in the sky.

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<v Speaker 1>The light they emanate comes not from a single point,

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<v Speaker 1>but from many individual points, all clustered together. These rarely

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<v Speaker 1>scintillate in unison, which is why planets and moons don't

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<v Speaker 1>twinkle as dramatically as the stars. So twinkling can only

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<v Speaker 1>happen an atmosphere is present. It's for this reason that

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<v Speaker 1>photos taken by the Hubble telescope looks so clear. There

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<v Speaker 1>aren't any atmospheric air pockets to refract the starlight. Earthbound

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<v Speaker 1>astronomers use telescopes with adaptive optics systems to compensate for twinkling,

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<v Speaker 1>making the stars look more stable. Today's episode is based

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<v Speaker 1>on the article why do stars Twinkle? On how stuff

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<v Speaker 1>works dot com, written by Mark Mancini. Brain Stuff is

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<v Speaker 1>production of by Heart Radio in partnership with how Stuff Works.

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<v Speaker 1>Dot com and it is produced by Tyler Clang with

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<v Speaker 1>assistance from Ramsey Young. For more podcasts from My Heart Radio,

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<v Speaker 1>visit the air heart Radio app, Apple Podcasts, or wherever

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<v Speaker 1>you listen into your favorite shows.