In addition to temperature, other criteria can be used to define different layers in the atmosphere. The ionosphere, for example, which occupies the same region of the atmosphere as the thermosphere, is defined by the presence of ions, a physico-chemical criterion. The region beyond the ionosphere is known as the exosphere. The ionosphere and the exosphere together make up the upper atmosphere (or thermosphere). The magnetosphere is the region above the Earth's surface in which charged particles are affected by the Earth's magnetic field.