Radio waves, like all forms of electromagnetic radiation, travel at the speed of light in a vacuum, which is approximately 299,792 kilometers per second (or about 186,282 miles per second). This speed is denoted by the symbol "c" in physics.
In space, where there is no significant medium to slow down or impede the propagation of electromagnetic waves, radio waves travel at this maximum speed. Whether it's radio waves, visible light, X-rays, or any other type of electromagnetic radiation, they all travel through space at the speed of light.
This means that radio waves emitted by stars, galaxies, or any other celestial objects travel across vast distances in space at the speed of light, enabling us to observe and detect them here on Earth using radio telescopes or other receiving devices.