That's only when you are thousands of feet away. In this case the light and the explosion were simultaneous. The light in the background was undoubtedly a floodlight already lit. Because such lights have reflectors, it would have reflected back the light pulse from the explosion.
That's only when you are thousands of feet away. In this case the light and the explosion were simultaneous. The light in the background was undoubtedly a floodlight already lit. Because such lights have reflectors, it would have reflected back the light pulse from the explosion.