The first thing to do to know the meaning of the term exosphere is to discover its etymological origin. In this case, we can state that it is a word that derives from Greek, since it is the result of the sum of several components of that language:
-The prefix “exo-”, which means “outside”.
-The noun "sphaira", which is synonymous with "sphere."
The exosphere is the outer region of a atmosphere : in the case of exosphere of planet Earth , begins at a distance of between 300 and 1,000 kilometers from the surface and extends to 10,000.
The concept, which can also be pronounced with emphasis on the third syllable (exosphere ), refers to the atmospheric layer in which the gas they disperse until they reach a composition similar to that of outer space.
The exosphere is the layer of the Earth's atmosphere that has lower density . It is on the thermosphere and it is in contact with the aforementioned outer space: that is why it is said to be a place of transit between the atmosphere and the interplanetary space.
Due to the little influence exerted by the force of gravity in the exosphere, some gases that are in this layer can escape and go to outer space. These gases, therefore, become diffused in the empty .
Another peculiarity of the exosphere is that, due to the small amount of particles that it covers due to the low density of the air , the heat is not transferred. The temperature is linked to the average speed of the atoms and molecules of a gas: the higher the speed of the particles, the higher the temperature. In the exosphere, the particles move very quickly, but this hot temperature is not transferred to the bodies due to the shortage of particles. A person feels the heat when the particles impact the skin and thermal energy transfer occurs, a situation that could not occur in the exosphere.
Other data of interest on the exosphere are the following:
-Its theoretical upper limit is 190,000 kilometers.
-It is considered to have a thickness that reaches 189,000 kilometers.
-In it the temperatures increase during what is the day and decrease during the night. Likewise, it must be borne in mind that it can record temperatures ranging between 0º and 1,700º C.
-From our planet, the part of the exosphere that is seen is the one called geocorone.
-Among the main functions that it fulfills is the fact that it comes to exercise as the first barrier of protection or defense of what is the Earth against the sun's rays. In the same way it acts as such before asteroids, meteors and even cosmic rays.
-In it the satellites have the particularity that they can orbit with remarkable ease. Why? Because there is very little friction in it.
-Thanks to the exosphere, the thermosphere can slow down its expansion. Otherwise, keep in mind that the atmosphere could not function properly.
It is important to mention, finally, that in the exosphere orbit various satellites artificial. Among them, meteorological satellites .