James Munro, age 12, of Calgary, Alb., Canada, for his questions

Where is the ionosphere?

An ion is a small particle charged with electricity, and a sphere, of course, is a round ball. The ionosphere is a layer of the atmosphere. It starts about 60 miles above our globe and reaches up to perhaps 650 miles. The countless ions in the ionosphere create an electrically charged blanket. Certain radio waves cannot pass through this barrier, and it acts as a sounding board. To bounce them back to earth.

Radio waves fan out in straight lines from a broadcasting station  they cannot bend. But some of those that angle up to the ionosphere are angled back to strike the earth miles from the station. There they can be picked up and sent on another pyramid trip to the ionosphere and back again.