IF YOU HAVE A THUNDERSTORM OUTSIDE:
Teach about an aurora then say "Some scientists believe that they make sounds because you can hear an odd noise when one appears. Auroras are 700 miles off the earth. You see how light comes way before sound when a t-storm is only 5-10 miles away? Then How could an aurora make a sound that is heard while it's seen when it's 700 miles off the earth. I want you to think on how this could happen and write it down. Scientists still wonder about the sounds." This is a great way to get kids to wonder about how you can hear the sounds immidiately. Say "No one knows if they are from auroras or just a major coincidence."