Thanks guys or ladies; I must confess that the "superman " idea didn't impress my grandson after I let him read all the answers you were kind enough to suggest. The "light waves" was the one he focused on the most. I was able to get him to understand it for awhile, but he called me this...
[FONT="Arial Narrow"][SIZE="2"][SIZE="2"]Imagine an event occurring on the moon that is not visible to the human eye, but with a high powered telescope it is easily viewed. Did the telescope see it happening in real time or did it see the event 1.32 seconds after it occured. Based on common...