The thermosphere is not divided into two parts in the way that other atmospheric layers like the troposphere and stratosphere are. However, it is often further categorized into two regions:

* Exosphere: This is the outermost layer of the thermosphere, blending seamlessly into space. It's characterized by extremely low density and is where satellites orbit.

* Ionosphere: This is the lower region of the thermosphere, where solar radiation ionizes gas molecules, creating a layer of charged particles. This layer is crucial for radio communication and is responsible for phenomena like the aurora borealis.

While these two regions are commonly used to describe the thermosphere, it's important to remember that these divisions are not as distinct as those found in other atmospheric layers.