You're likely thinking of the ionosphere. This layer of the Earth's atmosphere is located between 50 and 1,000 kilometers (31 to 621 miles) above the surface.

Here's why it's important:

* Charged Particles: The ionosphere gets its name because it's filled with ions and free electrons created by solar radiation stripping electrons from atoms.

* Radio Communication: The ionosphere reflects radio waves, making long-distance communication possible.

* Auroras: The Northern and Southern Lights are created by charged particles from the Sun interacting with the ionosphere.

* Spacecraft: The ionosphere affects spacecraft orbits and can cause drag.

Let me know if you'd like to learn more about any of these aspects!