Green orb appears darts across sky and blinks out

I was sitting outside during work in a parking lot with a group of 3 other friends. It was dark and I was facing west talking to 2 friends who were facing towards me. All of a sudden, fairly low in the sky I see a large green orb appear. It then darts westward over the Mississippi River and then blinks and disappears. It moved so fast. The other friend who was next to me stated that he saw a light pop up out for the corner of his eye and saw a green ball going through the sky. It seemed to low and fast to be a comet.