Answer:
The speed of light through empty space is constant regardless of the state of motion of the observer.
Step-by-step explanation:
One of the two postulates of special relativity states that:
As measured in any inertial frame of reference, light is always propagated in empty space with a definite velocity that is independent of the state of motion of the emitting body.
In other words, no matter where you are or how fast you move, light always travels at the same speed through empty space.