How epic solar winds make brilliant polar lights - Michael Molina

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Why do we see those stunning lights in the northern- and southernmost portions of the night sky? The Aurora Borealis and Aurora Australis occur when high-energy particles are flung from the Sun's corona toward the Earth and mingle with the neutral atoms in our atmosphere -- ultimately emitting extraordinary light and color. Michael Molina explains every step of this dazzling phenomenon.

Lesson by Michael Molina, animation by Franco Barroeta.

Every second,

one million tons of matter
is blasted from the Sun

at the velocity
of one million miles per hour,

and it's on a collision course with Earth!

But don't worry,

this isn't the opening
of a new Michael Bay movie.

This is The Journey of the Polar Lights.

The northern and southern lights,
also known as the aurora Borealis

and aurora Australis, respectively,

occur when high energy
particles from the Sun

collide with neutral atoms
in our atmosphere.

The energy emitted from this crash
produces a spectacle of light

that mankind has marveled at
for centuries.

But the particles' journey
isn't just as simple

as leaving the Sun and arriving at Earth.

Like any cross-country road trip,
there's a big detour

and nobody asks for directions.

Let's track this intergalactic voyage

by focusing on three
main points of their journey:

leaving the Sun, making a pit stop
in the Earth's magnetic fields,

and arriving at the atmosphere
above our heads.

The protons and electrons
creating the northern lights

depart from the Sun's corona.

The corona is the outermost layer
of the Sun's atmosphere

and is one of the hottest regions.

Its intense heat causes the Sun's hydrogen
and helium atoms to vibrate

and shake off protons and electrons

as if they were stripping off
layers on a hot, sunny day.

Impatient and finally behind the wheel,

these free protons
and electrons move too fast

to be contained by the Sun's gravity

and group together as plasma,
an electrically charged gas.

They travel away from the Sun
as a constant gale of plasma,

known as the solar wind.

However, the Earth prevents the solar wind
from traveling straight into the planet

by setting up a detour, the magnetosphere.

The magnetosphere is formed
by the Earth's magnetic currents

and shields our planet
from the solar winds

by sending out the particles
around the Earth.

Their opportunity to continue the journey
down to the atmosphere

comes when the magnetosphere is
overwhelmed by a new wave of travelers.

This event is coronal mass ejection,

and it occurs when the Sun shoots out

a massive ball of plasma
into the solar wind.

When one of these coronal mass ejections
collides with Earth,

it overpowers the magnetosphere
and creates a magnetic storm.

The heavy storm stresses the magnetosphere
until it suddenly snaps back,

like and overstretched elastic band,

flinging some of the detoured
particles towards Earth.

The retracting band of the magnetic field
drags them down to the aurora ovals,

which are the locations
of the northern and southern lights.

After traveling 93 million miles
across the galaxy,

the Sun's particles finally produce
their dazzling light show

with the help of some friends.

20 to 200 miles above the surface,

the electrons and protons meet up
with oxygen and nitrogen atoms,

and they sure are happy to see each other.

The Sun's particles high five the atoms,
giving their energy

to the Earth's neutral
oxygen and nitrogen atoms.

When the atoms in the atmosphere
are contacted by the particles,

they get excited and emit photons.

Photons are small bursts of energy
in the form of light.

The colors that appear in the sky

depend on the wavelength
of the atom's photon.

Excited oxygen atoms are responsible
for the green and red colors,

whereas excited nitrogen atoms
produce blue and deep red hues.

The collection of these interactions

is what creates the northern
and southern lights.

The polar lights
are best seen on clear nights

in regions close to magnetic
north and south poles.

Nighttime is ideal

because the Aurora
is much dimmer than sunlight

and cannot be seen in daytime.

Remember to look up at the sky
and read up on the Sun's energy patterns,

specifically sunspots and solar flares,

as these will be good guides
for predicting the auroras.