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  • (orchestral music)

  • - The Northern Lights are beautiful and odd

  • and they've understandably inspired

  • tons of myths over the years.

  • Like the vikings thought they were a bridge to Asgard

  • where Thor and the other gods live.

  • And another Norse legend says that

  • they're the light reflected off the Valkyrie's shields.

  • And then people in Finland thought it was

  • the archangel Michael, John Travolta,

  • fighting Beelzebub the Devil.

  • The problem is, those are wrong,

  • wrong, wrong, they're all wrong.

  • It was actually Galileo Galilei,

  • the famous early astronomer and

  • recanter of science, who gave the Northern Lights

  • their name, the Aurora Borealis,

  • which in Latin means Dawn of the North.

  • But it wasn't until Norwegian scientist Kristian Birkeland

  • in 1896, figured it all out that we came

  • to fully understand what causes the Northern Lights.

  • See, in the center of the Earth you will find

  • hot molten iron just roiling around

  • under tremendous gravitational pressure.

  • And, this roiling effect of the molten iron

  • creates magnetic fields that shoot out

  • from the center of Earth through the crust

  • and into the space around the planet.

  • That forms what's called the magnetosphere

  • and it's good thing we have it.

  • Because we're constantly being bombarded by

  • charged particles from the sun.

  • The sun is so hot that it exists

  • in a fourth state of matter.

  • There is gas, liquid, solid, and then plasma.

  • And in plasma, ions, which are positively charged atoms,

  • and electrons, just float freely around one another.

  • And these particles have such a high energy charge

  • that they can escape the massive gravitational field

  • of the sun and barrel toward Earth

  • at something like a million miles an hour

  • like a shotgun blast full of solar hate.

  • That's called the solar wind.

  • When these particles encounter our magnetosphere,

  • most of them just kind of bounce harmlessly off.

  • The Earth is saved.

  • But, some of them manage to get through

  • at the places where the magnetosphere

  • is weakest at the north and south poles.

  • You follow me?

  • When the electrons that make it through our magnetosphere

  • and into our atmosphere encounter

  • oxygen and nitrogen, the electrons transfer energy

  • to these atoms and excite them.

  • And to calm back down, the oxygen and the nitrogen

  • have to shoot off some of this energy

  • which they do in the form of

  • tiny packets of light called photons.

  • Beautiful beautiful photons.

  • Depending on where in the atmosphere

  • the electrons interact with the oxygen or the nitrogen,

  • different colors will be produced.

  • Like for example, oxygen, up to about 150 miles,

  • will produce a nice yellow-green color

  • when electrons bombard it.

  • Above that it emits a nice red color.

  • And then nitrogen up to about 60 miles into the atmosphere,

  • puts out a really beautiful blue.

  • And all of these colors can mix together,

  • forming beautiful glowing pinks and purples and whites.

  • It's like Miami Beach up there.

  • So this interplays is most vibrant during solar storms

  • which depend somewhat on the solar cycle.

  • And, it's always going on.

  • But the thing is you can't see the Northern Lights

  • during the day because they tend to be

  • outshined by the sun.

  • So tell us, have you ever seen the Northern Lights?

  • Let us know in the comments section below.

  • And while you're down there, don't forget to subscribe.

  • And for even more awesomeness,

  • visit our website at brainstuffshow.com.

(orchestral music)

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B2 中高級 美國腔

北極光是由什麼構成的?(What Causes The Northern Lights?)

  • 32 0
    sherryyou 發佈於 2021 年 07 月 26 日
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