Question

What is the density of the thermosphere?

Answer 1

Density of any atmospheric layer of earth is the measure of the amount of total gas that is present in a certain volume of space. As a formula the density is directly proportional to the mass and inversely proportional to the volume V:
$\rho =\dfrac{\text{m}}{\text{V}}$

Complete answer:
The thermosphere is the 4th layer of the earth's atmosphere that is also known by the name of ionosphere. It is located between the mesosphere and the exosphere, and is extended between 500 and 1000 kilometres of the earth's surface.
This layer absorbs and reflects much of the ultraviolet radiation, gamma rays and X rays originated by the sun. Due to absorption of these rays, a constant ionization process of various types of molecules takes place. That is why this layer is also known as the ionosphere. The ionized gases trapped in the layer raise the temperature by several hundred degrees and it is for this reason the layer is named thermosphere.
Although the thermosphere is considered as a part of Earth's atmosphere, the air density is so low in this layer that most of the thermosphere is what we normally think of as outer space. The space shuttles orbit Earth within the thermosphere.
The density of the thermosphere varies on the average from $1.8\times {{10}^{-8}}\text{ g c}{{\text{m}}^{-3}}$ to $1.8\times {{10}^{-15}}\text{ g c}{{\text{m}}^{-3}}$.

Additional information:
The natural phenomenon known as the Aurora Borealis occurs when electrically charged particles from the sun collide with gaseous particles in the thermosphere.

Note:
The thermosphere is very important for human life as it contributes enormously to protecting the earth, as well as promotes space exploration and communication. It absorbs much of the sun’s ultraviolet and X-ray radiation. This helps protect the earth from the extremely cold temperatures that come from space.