Have you ever wondered what air is and how it got here? Let’s dive into the fascinating story of Earth’s atmosphere!
Our planet’s atmosphere began forming around 4.6 billion years ago, shortly after Earth itself cooled down. Back then, the universe was filled with hydrogen and helium, and it’s likely that these gases were part of Earth’s early atmosphere. However, because Earth was so close to the Sun and quite hot, these lighter gases escaped into space. Meanwhile, planets like Jupiter and Saturn, which are farther from the Sun and much larger, managed to hold onto their hydrogen and helium.
As Earth cooled, radioactive elements decayed, and the remaining materials turned into solids, liquids, and gases. Scientists believe that comets and meteors bombarded Earth, bringing with them water vapor and other gases like krypton and xenon. Another idea is that volcanoes released water vapor into the sky. Either way, Earth’s early atmosphere was a mix of water vapor, carbon dioxide, ammonia, methane, and neon.
Around 4.5 billion years ago, asteroids, including a massive one that helped form the Moon, impacted Earth. This event might have blown away some gases, leaving behind a mix that allowed a new atmosphere to form. Volcanic activity and the planet’s internal heat contributed to this secondary atmosphere, which included nitrogen, carbon dioxide, and water vapor.
About 2.7 billion years ago, the first simple life forms appeared. These organisms didn’t need oxygen and lived by using sulfates for energy. Later, cyanobacteria, also known as blue-green algae, evolved. They used sunlight and carbon dioxide to produce oxygen through photosynthesis. Over time, these tiny organisms added more and more oxygen to the atmosphere.
Eventually, the amount of oxygen in the atmosphere increased so much that it caused a mass extinction of organisms that couldn’t handle it. However, microorganisms that could use oxygen survived, and over millions of years, they helped create an atmosphere that could support oxygen-breathing animals, like the ones we see today.
As Earth continued to cool, water vapor condensed and fell as rain, forming oceans. This rain also absorbed carbon dioxide from the atmosphere. Cyanobacteria spread throughout the oceans, producing even more oxygen. Oxygen is rare on most planets because it reacts easily with other elements, but on Earth, it reached a balance of about 21 percent, which is still being studied by scientists.
Today, Earth’s atmosphere is made up of 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.03 percent carbon dioxide. The remaining 0.07 percent includes water vapor, hydrogen, ozone, neon, helium, krypton, and xenon.
If you have more science questions, feel free to ask! We’re always excited to explore new topics. And if you’re interested in space, join us for our SpaceOut event on July 30th at 4 PM Pacific. We’ll be chatting with NASA scientists who work with the Mars rover Curiosity. Don’t miss out!
Thanks for reading, and stay curious!
Using the information from the article, create a timeline that shows the major events in the formation of Earth’s atmosphere. Include key events such as the birth of the atmosphere, the role of volcanoes, the rise of oxygen, and the Great Oxygenation Event. Use drawings or digital tools to make your timeline visually engaging.
Conduct a simple experiment to understand how volcanic eruptions can release gases into the atmosphere. Use baking soda and vinegar to simulate a volcanic eruption and observe the gas release. Discuss how real volcanoes contributed to Earth’s atmosphere by releasing gases like water vapor and carbon dioxide.
In groups, role-play the Great Oxygenation Event. Assign roles such as cyanobacteria, early organisms, and oxygen-breathing animals. Act out the process of how cyanobacteria produced oxygen and how it affected other organisms. Discuss the impact of this event on the evolution of life on Earth.
Create a poster that illustrates the composition of Earth’s current atmosphere. Include percentages of nitrogen, oxygen, argon, and other gases. Use creative visuals and facts from the article to explain why Earth’s atmosphere is unique compared to other planets.
Participate in a class debate about the importance of oxygen in Earth’s atmosphere. One side will argue why oxygen is crucial for life, while the other side will discuss how life existed before oxygen was abundant. Use evidence from the article to support your arguments.
Sure! Here’s a sanitized version of the transcript:
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Now that is air… But what is that? And how did it get here? What’s with the air?
Hey everyone, Trace here for DNews. There’s a question going around Reddit Science right now that caught my eye: Where did Earth’s atmosphere come from? We started discussing it, and we weren’t sure either. “Atmosphere” literally means “sphere of air,” but “air” isn’t really accurate either—because that’s just what we have on Earth. Venus and Titan have atmospheres, in that gases permanently cover their surfaces; in fact, a number of bodies in our solar system have atmospheres—even the Sun.
The gases surrounding celestial bodies are held in space by the gravity of their host planets, which determines a lot about their makeup and potential to support human life. Our atmosphere came into being not long after the Earth cooled 4.6 billion years ago. As hydrogen and helium are extremely prevalent in the universe, chances are our atmosphere contained them too, early on. The Sun is 98 percent helium and hydrogen. However, as we were so close to the Sun and pretty hot ourselves, much of those lighter, faster-moving elements escaped Earth’s gravity. Jupiter, Saturn, and Uranus got to keep theirs because they were so far away and much more massive.
Scientists believe that as radioactive elements decayed and the Earth cooled, our remaining elements coalesced into solids, liquids, and gases. A 2009 paper published in the journal Science suggests that at this point, the Earth was hit by many comets and meteors, bringing water vapor, krypton, xenon, and other atmospheric materials. Another, older theory states it was volcanoes that released water vapor into the sky. We’ll leave it up to the researchers, but needless to say, at this point we know there was water vapor, carbon dioxide, ammonia, methane, and neon that they think was already present over our hot crust.
Yet another theory proposes that 4.5 billion years ago, when the proto-Earth was being impacted by asteroids—including a giant one that formed the Moon—the neon in our atmosphere was blown off, leaving behind a beneficial ratio of gases. From there, a secondary atmosphere began to form from volcanic activity and the leftover heat inside the planet. Heavier elements like nitrogen split out, forming 78% of our atmosphere today, along with carbon dioxide and water. As the planet cooled, life began to form, and they did the rest.
2.7 billion years ago, when the first primitive life forms emerged, they lived anaerobically, or without air. These extremophiles digested sulfates for energy, completely ignoring the atmosphere. Later, cyanobacteria, or blue-green algae, evolved to take in carbon dioxide and output oxygen using photosynthesis. These organisms are still around today. They use energy from the sun and carbon dioxide to produce oxygen.
Eventually, and scientists know it happened but are unclear how, there was so much oxygen in our air that it affected organisms that couldn’t process it, causing a mass extinction. Microorganisms that could utilize oxygen survived, as did the cyanobacteria, and over millions of years, they added enough oxygen to support the evolution of oxygen-dependent animals, which evolved into the living animals we see today.
As the planet continued to cool, the water vapor began to rain down, dissolving the carbon dioxide gases into it. The oceans were formed in this way, and the cyanobacteria spread, creating more oxygen. Oxygen is hard to find on most planets because it tends to react with everything. It rusts metals, burns easily, and can form water. So how it reached the balance of 21 percent that we have today is still being studied.
According to HowStuffWorks.com, our air is composed of 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.03 percent carbon dioxide. The remaining 0.07 percent consists of water vapor, hydrogen, ozone, neon, helium, krypton, and xenon.
Do you have other science questions? Ask them! We’re always looking for new topics. You can post your questions here in the comments or tweet them at us at DNews!
And if you’re interested in space topics, come join us on July 30th at 4 PM Pacific for our SpaceOut! This month we’re hosting NASA scientists who work with the Mars rover Curiosity. We’ll be hanging out for a whole hour asking questions and exploring what they’ve been doing on Mars for the last year. RSVP with this link to join!
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Atmosphere – The layer of gases surrounding Earth or another planet, held in place by gravity. – The Earth’s atmosphere is crucial for supporting life, as it contains the oxygen we breathe.
Oxygen – A colorless, odorless reactive gas that is essential for respiration and is a major component of the Earth’s atmosphere. – Plants produce oxygen during photosynthesis, which is vital for animals and humans to breathe.
Nitrogen – A colorless, odorless gas that makes up about 78% of the Earth’s atmosphere and is essential for plant growth. – Nitrogen is a key component of proteins and is necessary for all living organisms.
Carbon – A chemical element that is the basis of all known life on Earth, found in all organic compounds. – Carbon is present in the atmosphere as carbon dioxide, which plants use during photosynthesis.
Water – A transparent, tasteless, odorless, and nearly colorless chemical substance that is essential for all known forms of life. – Water covers about 71% of the Earth’s surface, mostly in seas and oceans.
Volcanoes – Openings in the Earth’s crust that allow molten rock, gases, and debris to escape to the surface. – Volcanoes can create new landforms and affect the climate by releasing ash and gases into the atmosphere.
Gases – Substances in a state of matter that have no fixed shape and are free to expand, such as air. – The greenhouse effect is caused by gases like carbon dioxide trapping heat in the Earth’s atmosphere.
Cyanobacteria – Microscopic organisms that are capable of photosynthesis and are believed to have contributed to the Earth’s oxygen-rich atmosphere. – Cyanobacteria are often found in aquatic environments and can form harmful algal blooms.
Planets – Celestial bodies orbiting a star, large enough to be rounded by their own gravity but not causing thermonuclear fusion. – Earth is one of the eight planets in our solar system, orbiting the Sun.
Hydrogen – The lightest and most abundant chemical element in the universe, often found in stars and gas giants. – Hydrogen is a primary component of the Sun, where it undergoes fusion to produce energy.
