It wasn't just Cats. There really is a layer in the ionosphere called the Heaviside Layer, or more formally the Kennelly–Heaviside layer: https://en.wikipedia.

It wasn't just Cats. There really is a layer in the ionosphere called the Heaviside Layer, or more formally the Kennelly–Heaviside layer: https://en.wikipedia.org/wiki/Kennelly–Heaviside_layer https://en.wikipedia.org/wiki/Kennelly–Heaviside_layer Today this is more commonly known as the E layer or E region, and it is much beloved by ham radio operators because of its intermittent nature. You never know when sporadic E skip will become available and you can use it to contact hams far away!