Myth vs Reality: Composition of Earth's Atmosphere

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This short segment addresses the misconception that Earth's atmosphere is mostly oxygen. 


Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with the NASA Earth Observatory (


Text, Myth vs. Reality
Myth. Earth's atmosphere is mostly oxygen.
Reality. Oxygen gas makes up less than 21% of the volume of Earth's atmosphere. The most abundant gas is nitrogen, which makes up more than 78%. Most of the remaining 1% is argon, with small quantities of carbon dioxide and other gases.