Why does the ionosphere reflect radio waves?
How or why do radio waves reflect the ionosphere? 
How are radio waves emitted? How do radio waves work in space? How do radio waves travel? What are the properties of radio waves? What are radio waves? Describe the layers of the atmosphere. What type of radio communication utilizes each of them? How do you measure radio waves? How and why does pulsars emit radio waves only on their poles? What is radio Wave? Why can't radio waves transmit through water? What are radio waves? What are some examples? What is meant by radio frequency waves? Why antenna radiates? How do the atmosphere, hydrosphere and lithosphere interact? If radiowaves are reflected from objects (i.e planets) and they can penetrate a bit in the surface, we could image the subsurface right? If radiowaves are reflected from objects (i.e planets) and they can penetrate a bit in the surface, we could image the subsurface isn't it? How are different atmospheres affected by cosmic rays? Can electromagnetic waves be reflected? Where exactly inside the antenna can be the cause of radio frequency propagation? How are cosmic rays affected by different atmospheres? Why does sound need a medium like air or water in order to travel, but radio waves do not? How do HAM Radio and a CB Radio differ? How do we convert electrical energy into radio waves? How many stars have human made radio waves reached? What percent of our galaxy does that represent? Why do radio waves and gamma rays pass through walls but visible light does not? What are some of the dangers of radio waves? What are the layers of atmospheres? Are insects able to feel radio waves? How does an antenna radiate? Can radio waves be converted into electrical waves?