8. How did Earth’s atmosphere emerge?

Earth’s atmosphere formed about 4.6 billion years ago from gases released by volcanoes and hot rocks. The current atmosphere is the result of the evolution of that early atmosphere.

At that time, Earth was a geologically active planet, with frequent collisions that melted much of its surface.

Volcanoes emitted gases such as water vapor, carbon dioxide, sulfur, and nitrogen. As the Earth cooled, the water vapor condensed and slowly formed the oceans.