We were driving 55-60 mph, south-west (?) on county highway when a large, round glowing ball of light flew past us on our right. after zooming past us, it continued flying just above the ground, below tree top level, straight for approximately 1/2 a mile before veering sharply to the right (north?). it was winter but pitch black outside. i saw no other lights anywhere, including house or street lights. the alternator had gone out in my pick-up and my friend came to rig batteries to my engine to hobble my vehicle home to be worked on. he had to get to work and we were still about 30 minutes from home without having to swap out batteries. the alternator stopped working 2 hours from home, on an indian reservation, around 11:00 in the morning, many hours before the sighting. my friend was in his truck behind me. we talked about it later but he doesn't know what we saw and doesn't necessarily believe in ufos. this thing was round like a ball and glowed solid green, no blinking and no other colors. the area where it was flying is marshy, field land, no other busy roads or houses that i could see.