Hello! Yes, the ionosphere is a layer of the atmosphere above the Earth. The main layers of Earth's atmosphere from bottom to top are the troposphere (0-7 miles, where we live!), the stratosphere (7 to 31 miles above us), the mesosphere (31 to 50 miles), the thermosphere (50-440 miles), and the exosphere (440 to 6200 miles). In addition to these main layers, scientists sometimes talk about smaller layers within these layers, or group layers together, depending upon what they are studying. For example, the ozone layer is located within the stratosphere. And the ionosphere is the region of the atmosphere that is ionized (atoms and molecules split into electrons and ions) by solar radiation. The ionosphere actually includes different layers of the atmosphere depending upon the time of day. During daylight hours, the ionosphere includes the mesosphere, thermosphere, and exosphere from about 31 to 621 miles. However, most of the mesosphere is not ionized at night, so auroras are normally seen only in the thermosphere and lower exosphere. The ionosphere forms the inner edge of the magnetosphere and is important because it affects radio propagation on Earth, in addition to being the region where the auroras occur.