While driving north on Highway 85, I spotted a spherical object approximately 500-600 in altitude while looking west – southwest about 5 miles south of Crestview, Florida. The spherical object appeared to move in a southerly direction very slowly, then hover for approximately 30 seconds. The object had a grey underlying color with a white to blue – white glow. While the object was hovering, I observed the glow to brighten intensely to a bright white color for approximately 5 seconds, then return to a blue – white glow. The object then began to move again in a southerly direction, then simply disappeared.