While visible light, radio waves, microwaves and X-rays seem very different to our senses, they are all part of the electromagnetic spectrum. All of these waves, electromagnetic radiation, move through a vacuum at the speed of light (3 x 108 m/s) and do not require a media to propagate. The only differences between these types of radiation are the amount of energy these waves contain. Radio waves have a wavelength of about two or three meters. Remember that two meters is about the size of a human being. An FM station broadcasting at 90 MHz is broadcasting at a wavelength of 3.3 meters. Visible light is at about 0.0000006 meters or 600 nm. (That is for yellow.)
For more on the electromagnetic spectrum, visit this NASA website.
http://imagine.gsfc.nasa.gov/docs/science/know_l2/emspectrum.html