Space, an endless tapestry of stars reaching toward infinity, scattered through its vastness are 100 billion planets on which life theoretically could exist.
If only one percent of that life is intelligent, there could be one million civilizations out there, and of that million is it conceivable that one discovered the secrets of space travel.
It is possible that ancient astronauts went in search of life beyond their own world and found it on the planet Earth. The existence of other intelligent beings in the universe intrigues the men of tomorrow's science.
If ancient astronauts did land here, what effect would they have on early earth men? Perhaps they were worshiped, fear, loved. Perhaps they brought gifts, a new world of knowledge, or simply the principal of the lever.
If we accept the premise that beings from another civilization visited her ages ago, then some of the mysteries from out past take on a new and startling light.