Exosphere
The exosphere represents the outermost layer of Earth’s atmosphere. Due to the low density of particles within this layer, the likelihood of particle collisions is minimal. This results in some particles, such as hydrogen, escaping into space and beyond Earth’s gravitational influence. The exosphere extends up to approximately 600 kilometers into outer space. The term “exosphere” derives from Greek, meaning “the outer layer.” This atmospheric layer predominantly consists of hydrogen, atomic oxygen, helium, and carbon dioxide. From space, the outer layer of the atmosphere appears as a nebulous zone, commonly referred to as the geocorona.
Other Atmospheric Layers
The atmosphere is composed of five distinct layers, including the exosphere. Below are the remaining layers of the atmosphere:
Troposphere
The troposphere is the lowest layer of the atmosphere, where humans reside. It extends from approximately 6 kilometers to 20 kilometers above sea level. In the lower third of this layer, humans can breathe normally, as this region contains about half of the atmosphere’s gases. In the troposphere, temperatures decrease with altitude owing to heat absorbed from the Earth’s surface by solar radiation.
Stratosphere
Situated above the troposphere, the stratosphere serves as the primary flight path for most aircraft and functions as a protective barrier for the Earth’s surface by absorbing ultraviolet radiation. This layer is characterized by a significant concentration of ozone and features air movement parallel to the planet’s surface, extending from 6 kilometers to 20 kilometers above the ground.
Mesosphere
The mesosphere is notable for its extremely low temperatures, which can plunge to as low as 143 degrees Celsius below freezing. This layer stretches from approximately 50 kilometers to 85 kilometers above the Earth’s surface.
Thermosphere
In the thermosphere, temperatures can reach extremely high levels; however, this heat has minimal impact on humans due to the sparse particle density, which is insufficient for effective heat transfer. The thermosphere is the thickest of the inner atmospheric layers, extending up to approximately 513 kilometers. Notably, the International Space Station orbits within this layer of the atmosphere.