There is a tribe in Western Africa known as the Dogon people. They have a tradition of having been visited by beings who taught them various skills. The Dogons explain that these beings come from the sky, from a star we know as Sirius. The Dogons explain that this star is actually two stars, one of which cannot be seen. One star circles the other.
Much is made of this astronomical knowledge. How can the Dogons, without telescopes or other scientific equipment, know about Sirius? Even Western science didn’t know of Sirius until just over a hundred years ago. Surely this is clear proof of aliens.
Yes, it’s possible that aliens came and told the Dogons about Sirius, and then the Dogons taught this knowledge to their young. But it’s not likely.
Does it not seem more likely that some explorer happened to mention that Sirius – a bright star readily recognized by the tribe – is a double star?
Someone told the Dogons. The question is whether it was aliens, or earthly explorers who happened to encounter the tribe.