Bright blue light covered sky on clear night while driving on highway.As we were driving along a stretch of rural highway, all of a sudden, a blue light covered the sky above us in all directions. It was almost as if someone had turned the lights on up above us. Its short duration first made us think it was lightning, however, a closer look at the sky showed that there were no clouds. The sky was perfectly clear and the stars were shining bright. We pulled over about a mile later and got out to look things over. We didn't see anything above us but stars. No moving lights at all. It definitely freaked us out as this was the first time anything like this has happened to us.