On a recent trip with my partner heading towards Big Bend State Park , just past Marathon Texas. While driving around noon on a sunny day ,I noticed a shadow cross over the hood of the car. I thought it was probably a bird casting a shadow . Within seconds out of the corner of my right eyes I saw something very bright heading towards the passenger side of the window at a rapid speed . I turned my head towards the passenger window and noticed that my companion was staring out at the same object. It looked like a extremely bright form with blowing armlike extensions faster than seconds it appeared to pass thru the car . The entire car interior was white , absolute white , I could not see anything outside nor inside, although I was still facing the passenger .The stereo was on but I dont remember any sound either just glowing bright light. I��� have no idea how long the form took to pass completely thru the car . The car seemed to move back and forth with a jolt . The next thing that I remember is that my hands grabbed the steering wheel and I turned towards my partner and said " Why are we doing this ." We apparently were still facing each other , he has a terrified look on his face and shakes��� his head. I said " What happened ?" He said something hit the car.��� I reached out and stopped the swinging motion of the cross hanging from the rear veiw mirror . Realizing that the swinging motion supported the fact that the car had moved voliently. I look in the rear veiw miror to see if anything was behind the car , as if I had hit something. Their is noithing behind us .Both of us turn and look out of the window trying to determine what had slammed into the automobile . Nothing around us behind us . I almost stopped but thought that whatever had hit the car might somehow somewhere be outside . I slowed down still visually searching for some kind of animal , object , thing but nothing seemed visible.Let me mention that it was around noon on a clear day. I had a CLEAR mind and was in a calm mood . I am a logical person and do not seek fiction in life . Factual and senseable . This is a occurance that both my partner and myself witnessed at the exact same time .