Timeline of Earth’s Different Atmospheres:
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4.6 billion years ago: Earth forms, and its atmosphere begins to take shape. The initial atmosphere is composed mainly of hydrogen and helium, similar to the composition of the early solar system. (Source: Scientific American)
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4.4 billion years ago: Volcanic activity releases gases such as water vapor, carbon dioxide, and nitrogen into the atmosphere. These gases contribute to the formation of a secondary atmosphere. (Source: Scientific American)
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4 billion years ago: The secondary atmosphere starts to develop as volcanic activity continues. It consists of water vapor, carbon dioxide, nitrogen, and smaller amounts of methane and ammonia. (Source: Scientific American)
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3.8 billion years ago: The first evidence of life appears on Earth in the form of single-celled organisms. These early life forms, known as prokaryotes, release oxygen through photosynthesis, gradually altering the composition of the atmosphere. (Source: Scientific American)
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2.5 billion years ago: Oxygen levels in the atmosphere increase significantly due to the proliferation of photosynthetic organisms. This leads to the formation of the third atmosphere, known as the oxygen-rich atmosphere. (Source: Scientific American)
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2 billion years ago: The oxygen-rich atmosphere allows for the evolution of more complex life forms, including eukaryotes. These organisms have more advanced cellular structures and can thrive in the presence of oxygen. (Source: Scientific American)
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600 million years ago: The oxygen levels in the atmosphere continue to rise, reaching levels similar to those of today. This increase in oxygen enables the evolution of multicellular organisms, leading to the Cambrian explosion of life forms. (Source: Scientific American)
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Present day: Earth’s atmosphere consists primarily of nitrogen (78%) and oxygen (21%), with trace amounts of other gases such as carbon dioxide, methane, and ozone. This composition supports the diverse ecosystems and life forms found on our planet today. (Source: SciJinks)
Note: The provided articles were used as sources to create this timeline.
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