How Did the Earth's Atmosphere Come to Earth?
The atmosphere of Earth contains essential elements that sustain life. For example, the atmosphere includes oxygen, which people need to breathe and which is necessary for cellular respiration. Plants use carbon dioxide in the air in their own respiration processes. Since the Earth's atmosphere creates an environment in which organisms thrive, a discussion of how the Earth's atmosphere formed needs to be included in basic biological study.
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Stage 1
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According to the U.S. National Aeronautics and Space Administration (NASA), primitive, unstable Earth probably was made up primarily of hydrogen and helium gases that were near the sun. Heat energy excited the molecules of hydrogen and helium so much that they traveled back out into outer space.
Stage 2
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As the Earth released some of its heat energy and hydrogen and helium escaped into space, some of the gases that made up the Earth started to solidify into rock and magma that eventually would form the Earth's crust. NASA asserts that the Earth released gases water (steam), carbon dioxide, and ammonia through volcanic activity.
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Stage 3
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NASA claims that, despite the harshness of primitive earth, simple bacteria began to grow on the Earth. These early bacteria really were closer to plants, since they lived on sunlight and carbon dioxide, and because they gave off oxygen as a biproduct. These tiny bacteria used up great amounts of the carbon dioxide in the atmosphere and put back oxygen in its place. At the same time, the sun provided enough energy to break the ammonia molecules in the atmosphere apart. As a result, the atmosphere became full of hydrogen and nitrogen. Since hydrogen is very light, a lot of it escaped back into space. The Earth's atmosphere is still in this stage and is constantly changing, even though people may not notice the changes because they are so gradual.
Other Atmospheres
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The manner in which the Earth's atmosphere formed is similar to how the atmospheres of other planets form. All atmospheres form when light gases escape from a planet, leaving heavier gases behind. Depending on the energy and chemical processes present on the planet, these heavier gases may support life, or they may be broken down into other gases that do. This is why scientists are so interested in any planet with an atmosphere.
Concerns
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As of 2010, there is growing concern over the apparent thinning of the ozone layer in the Earth's atmosphere. The University of Michigan explains that the ozone layer is essential to life on earth because it blocks large amounts of heat and solar radiation from reaching the Earth's surface. People damage the ozone by releasing pollutants into the air. Additionally, these pollutants trap the heat energy that reaches the Earth into the atmosphere, which theoretically could raise the temperature of Earth to the point of Earth being uninhabitable. These concerns demonstrate that man has an impact on the continuous formation, stability and functionality of the atmosphere around the globe.
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References
- Photo Credit Earth image by Patrik Lidaj from Fotolia.com
