thumb|374px|link=The Atmosphere of Earth was a layer of gases surrounding the planet, Earth that was retained by Earth's gravity. The atmosphere protected life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (Greenhouse effect) and reducing temperature extremes between day and night (The diurnal temperature variation).
thumb|left|354px|link= The common name given to the atmospheric gases used in breathing and photosynthesis was air. By volume, dry air contained 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide and small amounts of the other gases such as methane. Air also contained a variable amount of water vapor on average around 1%. Although air content and atmospheric pressure varied at different layers, air suitable for the survival of terrestrial plants and terrestrial animals currently was only known to be found in Earth's troposphere and artificial atmospheres.
The Earth's Atmosphere was split into five layers. These are:
- Exosphere which was almost eighty percent of the outer atmosphere: >700 km (>440 miles)
- Thermosphere, lower base of the Exosphere: 80 to 700 km (50 to 440 miles)
- Mesosphere which housed the Northern Lights: 50 to 80 km (31 to 50 miles)
- Stratosphere where the meteors are seen: 12 to 50 km (7 to 31 miles)
- Troposphere, lowest layer where the planes flew: 0 to 12 km (0 to 7 miles)