Not the most appropriate place for this, but until posting in other topics gets sorted out, this will have to do.  An interesting article on alien probes/visitors and some reasons for why we haven't found any evidence yet.

http://news.discovery.com/space/are-alien-artifacts-in-our-solar-system.html

I particularly liked this excerpt:

"In a paper published in the 1960s Carl Sagan, using the Drake Equation, statistically estimated that Earth might be visited every few tens of thousands of years by an extraterrestrial civilization.

If this is a reasonable estimate, then what evidence might have been left behind? (And pull-eeze – it's not the Great Pyramids, not the Nazca lines, and not Stonehenge!)"

Note: Arifact is an archaeic term for Artifact :)

Does Helen Thomas count?

Awaba said:

look up ooparts on google.  a few fakes – but some are intriguing.  yes, i am still lurking.

Yes, several of the things that fall into that catagory are interesting and bear investigation.  Others are even more interesting but have some issues with them.  One that is sometimes touted is the irradiated area in India that then goes into old texts describing a sky battle and an explosion or series of explosions.  Rather intriquing when you read the descriptions.  These texts apparently do exist, but this particular one is interesting in that it all seems to be traceable to a "World Island Review" article from January 1992 published in the UK…unfortunately, this magazine appears to be ficticious and many of the references all point back to it as their origin.

Do a search for "World Island Review" and you'll get numerous results all telling the same story…the search term shows up, though, only as "according to an article in World Island Review" and I've yet to find the actual publication.

Some were not necessarily deliberate fakes but misunderstood such as what appeared to be an ancient spark plug but because it was an accretion that contained an early 20th century spark plug, it was thought to be much older since there were other much older objects in the accretion (which does not in any way date the material as a whole)