changes throughout its lifetime
So many of Earth’s features today, from our blue sky to life itself, depend on the atmosphere surrounding the planet, but it has taken billions of years to evolve to where it is today. This post will explore the evolution and progression of Earth’s atmosphere as well as the processes that led to these changes.
After Earth’s birth from dust and rocks orbiting the young sun, its atmosphere was mostly composed of Hydrogen and Helium, as those elements made up a vast amount of the material in space. Earth, however, was not massive enough to retain these light elements and eventually they were able to attain escape velocity and this atmosphere was lost like can be observed with Mercury. This might have been the end of the story, but Earth contained many volcanoes that released gas from the planet’s interior into the atmosphere in a process called outgassing. This process of outgassing created an atmosphere with increased amounts of water vapor, nitrogen, and carbon dioxide. As Earth continued to cool down, that water vapor condensed, eventually creating oceans and lakes. Chemical compounds like carbon dioxide were dissolved in the condensing water and therefore removed from the atmosphere, leaving behind for the most part nitrogen.
The other major component of Earth’s atmosphere besides nitrogen is oxygen, a byproduct of photosynthesis. Over billions of years, the lifeforms living on Earth produced enough oxygen to drastically change the atmosphere and provide the oxygen we breath today. These three major phases are considered the essential steps for creating Earth’s atmosphere as we know it today.
