The Earth's atmosphere gradually changed over time as it was bombarded by asteroids and comets, adding heavier elements.
Here's why:
* Early Earth's atmosphere: The early Earth's atmosphere was indeed composed primarily of hydrogen and helium, the most abundant elements in the universe. This was due to the young Sun's intense solar wind pushing away lighter elements.
* Asteroid and comet bombardment: During the early stages of the Solar System, Earth was constantly bombarded by asteroids and comets. These impacts brought heavier elements like carbon, nitrogen, and oxygen to Earth.
* Volcanic activity: As Earth cooled, volcanic activity released gases like carbon dioxide, water vapor, and sulfur dioxide into the atmosphere.
* Evolution of the atmosphere: Over millions of years, these processes transformed the early atmosphere of hydrogen and helium into the nitrogen and oxygen rich atmosphere we have today.
Let me know if you have any other questions!
