The remaining gases are found in much smaller proportions ... was much more carbon dioxide but no oxygen in the early atmosphere. The composition of the atmosphere has changed over time, and ...

Meanwhile, hydrogen and other very light gases drift deep into space. Our planet has a magnetic field that thankfully protects the atmosphere ... study the chemical composition of stars ...

These gases can enter terrestrial and aquatic ... Organisms may express both behavioral and physiological changes to atmospheric composition, resulting in large-scale and long-term responses ...