Beginning in the 1960s thousands of UFO landings flyovers and collisions have left scientific evidence behind for study. These events have become known in the field of UFOlogy as the "trace cases". There are over 3000 documented UFO physical trace cases and they have occurred in over 90 countries around the world. From impressions in the dirt burned or broken vegetation and trees to scientific abnormalities that have yet to be explained "trace cases" offer up some of the most convincing evidence of the UFO reality. Join US as we reveal what could possibly be evidence of "alien encounters".