eksosferës

The exosphere is the outermost layer of Earth's atmosphere. It is the region where the atmosphere gradually thins out and merges with outer space. There is no clear upper boundary to the exosphere, but it is generally considered to extend from the thermopause, around 500 to 1,000 kilometers (310 to 620 miles) above Earth's surface, up to about 10,000 kilometers (6,200 miles). At these altitudes, the density of atmospheric particles is extremely low.

Particles in the exosphere are so far apart that they rarely collide with one another. Instead, they move in ballistic trajectories, following the paths dictated by Earth's gravity and their own kinetic energy. Some particles have enough energy to escape Earth's gravitational pull entirely and drift off into interplanetary space. This is a key characteristic that defines the exosphere as the final frontier of our atmosphere.

The composition of the exosphere is primarily hydrogen and helium, the lightest gases. Oxygen and nitrogen, which are abundant in the lower atmosphere, are present in very small quantities here. Due to the extremely low density and the sparse presence of particles, the exosphere does not effectively absorb or reflect solar radiation. Temperatures in the exosphere are theoretically very high, as the few particles present can be heated by solar radiation, but the concept of temperature is not well-defined in such a rarefied environment. Satellites, such as the International Space Station, orbit within the exosphere.