Ever since we realized there were other stars out there — and other planets — we’ve been obsessed with the possibility of extraterrestrial life. Stories of meeting beings from other worlds fill up the box office and the bestseller lists, and pretty much everyone on Earth agrees, there must be life out there somewhere. As years go by with no contact, however, some are starting to wonder why it’s taking so long.

The answer may simply be that like anything involving the huge distances and faint signals of space, meeting aliens is hard. In fact, it’s quite possible we’ve already been contacted — and we didn’t notice. Here are four scenarios that could lead to us missing out on the greatest moment in human history. Continue reading →