How was the Earth’s atmosphere formed?
The Earth and the rest of the solar system were formed about 5 billion years ago. Gases swirling around the sun gradually cooled and formed masses called minor planets. One of these minor planets was the Earth. The newly formed Earth was showered by countless minor planets, small meteorites, and other objects. The materials in these minor planets and meteorites were released as gases that eventually formed the atmosphere that covers the earth.
Originally, there was no oxygen in the atmosphere. It was made up mainly of carbon dioxide, water vapor, and methane gas. Not even clouds could form because the atmosphere was so hot and dry. It took a very long time for the atmosphere to become what it is today.
