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In the year 2000, a German satellite called CHAMP was launched into orbit to study the
Earth’s atmosphere.
As it flew over the North Pole, it came across a dense pocket of air which started to slow
the satellite down.
Although the atmosphere is almost non-existent at this altitude, there are still small traces
of atmosphere floating around.
But when CHAMP passed through the pocket of air, it measured an increase in air density
of almost double the expected value.
Scientists weren’t aware at the time, but this pocket of dense air was being caused
by an aurora.
These dazzling displays of light have fascinated the human race for centuries.
Unlocking the mystery of auroras took hundreds of years - and today, scientists are still
learning more.
Deep in the Arctic tundra, researchers are studying a different kind of aurora which
is causing our atmosphere to leak into space.
Records of auroras date back to prehistoric paintings - but the first scientific observation
was made in 1790 by scientist Henry Cavendish.
He used triangulation to estimate that auroras were taking place around 100 kilometers above
the Earth’s surface.
Over time, scientists learned that auroras are an effect of how the Sun interacts with Earth.
Earth has a magnetic field which protects us from the Sun’s solar wind.
These solar winds are made up of charged particles which shoot out from the sun with enormous
amounts of energy.
When the charged particles arrive at Earth, most of them are deflected by our magnetic field.
But at the North and South poles, they can sneak through and briefly interact with our atmosphere.
These charged particles transfer their energy into the particles of our atmosphere when they collide.
This interaction releases energy in the form of light, creating the beautiful display we
know as the aurora.
Specific colors of light are released depending on the type of particle and the amount of
energy being transferred.
Despite the enormous amounts of energy involved in auroras, the particles quickly return to
a normal state and our atmosphere is unharmed.
For a while, scientists believed that oxygen was too heavy to escape Earth’s gravity
- so when CHAMP discovered pockets of air at unusually high altitudes, they weren’t
worried about it leaving Earth.
But when scientists started to study the near Earth regions of space, they found large amounts
of ionized oxygen which could only have originated from Earth.
Somehow, the oxygen particles in our atmosphere were getting enough energy to escape Earth’s
gravitational pull.
The north and south poles are the only points where our magnetic field comes into contact with Earth.
The magnetic field lines run parallel with most of the Earth’s surface
but curve towards each pole.
When the Sun’s charged particles arrive at Earth, they are forced to travel along
the magnetic field lines, causing most of them to meet at the poles where they interact
with Earth’s atmosphere.
At this point, the charged particles have a direct path through to our atmosphere.
This gap in our magnetic field creates a phenomenon known as the ‘cusp aurora’.
With cusp auroras, solar winds are accelerated through the gap, creating a very concentrated
area with intense heat and kinetic energy.
As the charged particles collide with the particles in our atmosphere, they receive
enough energy to escape Earth’s gravitational pull, causing streams of oxygen to leak into space.
While a normal aurora can be observed almost every night in the Arctic, the cusp aurora
only appears at midday when the arctic experiences a full day of darkness.
To make it even more difficult to observe, the cusp doesn’t have a fixed position and
it constantly moves around the Arctic regions.
But when these colorful lights finally appear, it signals that hundreds of tons of oxygen
are escaping Earth’s atmosphere.
Although this can only be observed for a short period of time each day, this is only a fraction
of what is actually happening.
When we look at the Earth in ultraviolet light, we can see that auroras are constantly happening
throughout the day.
But Earth is not the only planet to experience auroras.
The Hubble Space Telescope was able to capture a very similar aurora process happening on
Jupiter by viewing it in ultraviolet light.
Mars used to be a lot like Earth, but the solar wind stripped away its atmosphere over
billions of years, leaving small magnetic fields dotted around the planet.
Eventually, our atmosphere will experience a similar fate.
Every day, over 100 tonnes of our atmosphere escapes into space.
Fortunately, at this rate, it would take billions of years for our atmosphere to completely disappear.
And while auroras are one of the many wonders of our night sky, the process behind them
is a shocking reminder of how fragile our planet really is.
While doing research for this video, the most fascinating bits of information were
hidden away in various books and research papers.
It’s 2020 and most of us don’t have the time to fully dive into a book and absorb
all of its information.
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