First of all, Happy Thanksgiving to you all! Now, my question: I'm on earth viewing through a telescope. I observe a car in outer space, traveling roughly at right angles to me (i.e., across my scope's field of view, let's say left to right). That car, a 1956 Chevy (irrelevant, but my favorite car) according to its speedometer, is traveling 1/2c. It turns on its headlights. He measures the speed of light emanating from his headlights as traveling c. I measure the light traveling from his headlights as c. Question: What do I measure the car's speed as being? Thanks.