The Ionosphere is a layer of electrons and ionized atoms and molecules that stretches from approximately 30 miles (48 km) above the Earth’s surface to the edge of space at about 600 miles (965 km) high. This dynamic region actually grows and shrinks depending on solar conditions. The Ionosphere overlaps into the mesosphere and thermosphere and includes 3 sub-regions: D, E, and F. Notably, the Ionosphere makes radio communications possible and forms a crucial link in Sun-Earth interactions. It’s also where most auroras form.