The Phoenix Lights was an otherworldly event witnessed by thousands of Arizona residents over a 300 mile span on March 13, 1997. On February 3, 2015, the Phoenix lights returned.

Witnesses claim to have observed a huge V-shaped (several football field sized), coherently-moving dark UFO (stars would disappear behind the object and reappear as it passed by), producing no sound, and containing five spherical lights or possibly light-emitting engines. Fife Symington,[2] the governor at the time, was one witness to this incident. As governor he ridiculed  the idea of alien origin,[3] but several years later he called the lights he saw "otherworldly.

Source:  http://en.wikipedia.org/wiki/Phoenix_Lights