(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.
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visit our website at brainstuffshow.com.
