Just out of curiosity, have you ever come across the Dogon tribe? I have a recollection of reading a National Geographic years ago, which contained a story of some French explorers who visited the Dogon tribe in Africa I believe. While there, the tribe shared with them knowledge of a sister star to Sirius, which could not be seen with the naked eye. This information was later passed to astronomers who then found the star.
The tribe claimed to have been given the information by aliens visiting Earth.
While typing this, I thought I'd have a quick Google and found these links - worth a read if you CBA:
http://en.wikipedia.org/wiki/Dogon_people#Dogon_and_Sirius
http://www.bbc.co.uk/dna/h2g2/A2754524
Part of me thinks it's nonsense, but equally, what if it were true? The possibility fascinates me