DENVER - May 15, 2012 - The Federal Aviation Administration is investigating a mystery in the sky. A mysterious object flying over Denver nearly caused a mid-air collision Monday evening, 9Wants to Know has learned. As far as investigators know, the mystery object did not show up on radar Monday. Investigators believe this object, whatever it is, could pose a serious safety hazard to planes. VIDEO: http://www.9news.com/news/article/268207/188/Mystery-object-nearly-causes-mid-air-collision