The hype about aliens visiting earth pretty much peaked in the sixties when the Apollo astronauts landed on the moon, proving that it is possible to travel between planetary bodies. When asked what proof there is that aliens have visited earth, most believers would like to show you artifacts that are definite evidence of alien visitation. Take the great pyramids for example, for years the believers have been saying that they had been built by aliens. After all, no one knew how anything that big could be built without modern machinery. Well we know now. The great pyramids were built-up using ropes and pulleys (and let's not forget slaves) to stack the giant limestone blocks. But how did the Egyptians move the blocks to the pyramids? The answer is water, ordinary water. The stones would be pulled on sleds across the desert sand. Someone, a slave, would pour water on the sand in front of the sled. This would greatly reduce the friction and allow the slaves pulling the sled to pull it more