Thanks, I never knew that.
I always thought radio signals traveled at somewhere below the speed of light.
Your welcome :-) BTW, a qualifier on this. All the frequencies travel at the same speed in a vacuum. In the atmosphere (or any other medium), the different wavelengths (frequencies) have a slightly different velocity. This is why a prism works to separate the different colors (frequencies) of light. The index of refraction is slightly different due to the velocity difference.
Your eyes are radio recievers. The rods and cones are antennae.