The atmosphere that we are now breathing is the _____ atmosphere Earth has had.

Question

Quizplus · Accepted Answer

The current atmosphere that Earth has is the third atmosphere it has had. The first atmosphere was formed from gases released by volcanic eruptions, but it was thin and lacked oxygen. The second atmosphere was formed from gases released by early life forms, which produced oxygen. The third and current atmosphere was formed about 2.5 billion years ago and has a composition of 78% nitrogen, 21% oxygen, and other gases such as water vapor and carbon dioxide.

The Atmosphere That We Are Now Breathing Is the _____