Origin of the atmosphere
4500 million years ago (Biology and Geology 4th ESO), our planet was a ball of fire surrounded by a large cloud of gas and dust. When it began to cool, the surface solidified, giving rise to the continents and the seabed. There were many volcanoes erupting, whose gases accumulated on the surface, creating an atmosphere different from the one we know today. The early atmosphere had a lot of water vapor, carbon dioxide, nitrogen, and other gases.
Millions of years later, when the earth's crust had already cooled, the water in the atmosphere turned into a liquid state and, after intense precipitation, the seas and oceans were formed, where life probably began.
Later life appeared and the atmosphere changed. Photosynthesis removed carbon dioxide from the atmosphere and passed it on to living things, while releasing oxygen into the atmosphere. When the atmosphere became enriched in oxygen, animals emerged, capable of breathing it.