Abstract:I first argue that the extraterrestrials we will find will not communicate, for the simple reason that they would likely be either immensely inferior or immensely superior to us. Then, I argue that the discovery of extraterrestrials will be slow, like other previous major scientific discoveries. I introduce a multidimensional model to assess and to prepare the impact of discovering extraterrestrial life. Twenty-six dimensions are introduced, illustrated with spider diagrams, which cover both what extraterrestrial might look like, and how humans may react.