If indeed ET has come calling there are several reasons I can think of that this is not general knowledge:

• They're much better at stealth than we are and make sure we didn't know they were here.
• ....because their Prime Directive says we aren't supposed to know.
• As a primitive planet in a backwater corner of the galaxy they are not motivated to come here
• we have nothing they need/want.
• Cowboy Niel

I've heard the argument that we are all alone in this universe and I just don't buy it. In fact I consider it the height of hubris to think we are so special that we are the only intelligent life in this universe. I think ET is out there but not too excited about the prospect of meeting us at this point.

I've also heard argument they have been here already (or even now) and I find myself questioning what ET's motivation would even be for doing so. Travel across interstellar distances is expensive no matter what your technology is. If ET has figured out FTL then ET might come by and check in on this place but I still say there are no resources or technology or anything else of value here to ET that would make the trip very worth it.

In saying all that I sincerely hope I'm proven wrong someday but for now ET is the province of speculation and science fiction novels.