KIDS ASK! Where Did The Air Come From? Part II

Here at High Touch High Tech, we teach a LOT of science, and the best part about it is feeding young scientists’ curiosity about this amazing world we live in!  Although our programs are jam packed with experiments, we make time to let our young scientists ask us whatever questions they’ve always wanted to ask a scientist.   

In the coming weeks, we will be sharing a special series of articles answering some of the most frequent questions that come up from our young partners in science.  Our question this week is:


Science is awesome for so many reasons, but one thing we love about learning science is how it helps you to think differently about things you don’t usually notice in your day-to-day life.  Like air.  Air is the source of our life, carrying oxygen to our cells so they can function.  We take about 20,000 breaths of air every day and if we’re lucky, we hardly ever have to think about it.  It’s easy to think of air as just, well…boring.  It’s just there, softly surrounding us and sometimes making cool breezes or big storms.   In fact, the layer of air around the earth, called the atmosphere, is such a rare, unique, unbelievably lucky mixture that we’ve never seen its equal anywhere else in the known universe. The story of how the air came to be is actually one of the most EPIC, amazing stories in all of science.  So what is this air we breathe?  Buckle up science friends, because the story of our air is a truly wild ride –it’s a story of ice ages, deep-sea volcanoes, mass extinctions, comets and no less than the beginning of all of LIFE! 

It’s a story SO epic, we had to tell it in two parts.  At the conclusion of our tale this week, you’ll never see the stuff in your lungs the same way again.


In our last episode, we left our dear young Earth cooling out after a mega-crash with another planet.   At the same time, a few million light years away, earth’s neighbors in the solar system were also forming.  Many of the planets in our solar system cooled and formed an atmosphere, which is a layer of gas that gravity pushes close to the planet.  Earth is not the only planet with an atmosphere. The atmosphere of Pluto is deadly carbon monoxide and methane.  The atmosphere of Venus is mostly poisonous carbon dioxide.  Jupiter’s is hydrogen and helium.

We’re basically the Goldilocks of the solar system.

Only on Earth are we lucky enough to have an atmosphere that is the right mix of oxygen and nitrogen.  Nitrogen actually makes up the most of our atmosphere today, about 78%.  Scientists think a lot of nitrogen came from comets and from volcanoes when the earth was forming.  The rest of our atmosphere is our good friend oxygen, just a little bit of carbon dioxide, and a few other gases like argon.  When you put oxygen and nitrogen together like we have on Earth, the oxygen is able to provide energy for living things, instead of being poisonous. 

If the different gases of today’s atmosphere were your hand.

Whew! Take  a deep breath! So …. the Earth’s formation was pretty wild, full of crashes and smashes and volcanoes and stuff — but now it’s ready with oxygen and nitrogen to support an epic variety of living things, right?  NOOOOPE!  The story of our atmosphere is even wilder than that!  About 4 billion years ago, as our Earth began to cool, the atmosphere was mostly carbon dioxide and a lot of water vapor.  Not great for life!  But then came the rain.  For a very long time, maybe as much as TWO MILLION YEARS STRAIGHT, the water vapor in the atmosphere cooled and fell to earth as rain.  Can you imagine a rainy day that lasted two million years? All that rain billions of years ago still makes up every lake, every ocean, and every stream on earth today. Water was there when Earth was very new and has been here on Earth ever since.

Like this, but for two million years.

Because comet strikes and a whole planet strike brought so much water to Earth when it first formed, the Earth became a water planet.  Earth’s water became key to creating the atmosphere you are breathing right now.  After Earth’s water settled into the oceans, rivers, and lakes, our beautiful Earth was cool and quiet… too quiet!  There was nothing alive on the planet.  Over another billion years, carbon in the atmosphere began to dissolve into the ocean, and mix with things like nitrogen.  Somehow, all of those different chemicals and elements that made up the early earth began to mix and clump together in the water, and over a long time, out popped the first living things!  Maybe it was a bolt of lightning that helped all of those compounds come to life?  Or perhaps, just like a lot of Earth’s nitrogen and water, microscopic life came to earth from space?

ESA/Rosetta/NAVCAM, CC BY-SA IGO 3.0CC BY-SA 3.0 IGO, via Wikimedia Commons

This is one of the best photos of a comet ever taken. There is recent evidence from scientists in Japan that comets do carry the kinds elements and compounds needed for life.

How life began on Earth is still one of the biggest questions in all of science.  We do know that Earth’s water was essential the beginning of life, and we do know that the earliest life were single-celled organisms called anaerobic bacteria.  Anaerobic bacteria were the first things to grow and reproduce.  It’s thought that Anaerobic bacteria began very deep in the ocean at hydrothermal vents, a type of underwater volcano, and got their energy from the minerals and chemicals in the water around the vents.  Anaerobic bacteria are still around today, closer than you think – lots of them are living around your teeth right now!  Anaerobic bacteria does NOT need oxygen to live. Oxygen is actually deadly to this bacteria.  At this time there was hardly any oxygen on the planet, so there was no problem! 

This is a deep-sea hydrothermal vent called “Lost City.” Using chemical analysis, scientists think life on earth may have begun right here.

Anaerobic life covered the planet until another life form, called cyanobacteria, emerged on the scene, and this little green friend has a lot to do with why you are breathing oxygen, and why you, or anything alive, are even here at all.  Basically, cyanobacteria murdered pretty much everything on the planet by making that oxygen you are enjoying right now. The tiny cyanobacteria did not need deep-sea chemicals for energy.  They used sunlight.  Sound familiar?  The reason we have lovely, life supporting oxygen for everyone is photosynthesis.  Photosynthesis is the amazing process still used by plants and bacteria today that takes the energy from sunlight, carbon dioxide, and water and turns it into sugars and oxygen.  Because cyanobacteria could use sunlight to feed and grow, soon they were everywhere on the planet.  That meant more and more oxygen was pouring into the atmosphere.  Oxygen, which is great for us…but DOOM for anaerobic life on earth at that time.  Mega-doom. According to some scientists, it was even-worse-than-the-extinction-of-the-Dinosaurs-mega-doom.

By 2.4 billion years ago, there was so much oxygen in the atmosphere, it caused a catastrophic extinction that scientists call The Great Oxidation Event.  It’s amazing enough that so much of our atmosphere came from awesome things like comets, planetary collisions, and huge volcanoes.  But the truth is, what’s in your lungs right now is also the byproduct of an absolutely deadly extinction event that changed the Earth forever.  At the time of the Great Oxidation Event, oxygen had spread through the atmosphere and into the ocean.  There was so much of it, it reacted with Earth’s iron and covered the ocean and land in rust.  It wiped out most of the anaerobic bacteria, and even a lot of the cyanobacteria too. Even worse, it changed the climate so much that Earth went into a massive ice age that froze the entire Earth like a giant snowball.  Nearly everything on Earth died – 90% of all life!  The 10% of tiny organisms that survived became the ancestors of all living things, even humans.  These little survivors adapted to the new oxygen-rich atmosphere, and were able to use the energy in it to grow from tiny bacteria into everything now alive on earth.  Including YOU: a person who now knows the epic truth of where the air came from!

Sources and Further Information:

That time it rained for two million years:

How life might have begun on our water planet:

How cyanobacteria evolved and took over the world:

How cyanobacteria almost wiped out all of life:

A deep dive on the Great Oxidation Event:

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