7.) Aliens Made a Big Show in 1997
Some people believe the "Phoenix Lights" seen over the Valley in 1997 are still a mystery. It's really not -- they weren't aliens. The Air Force explained that the lights hovering visible from Phoenix -- lights that just happened to be hovering over an Air Force range -- were some long-burning flares dropped by some National Guard planes during a training exercise. Multiple physicists who conducted independent research based on the evidence found this explanation perfectly acceptable.