Not quite, radio waves can diffract around obstacles/edges, and lower-frequency waves apparently do this more efficiently. https://en.wikipedia.org/wiki/Ground_

Not quite, radio waves can diffract around obstacles/edges, and lower-frequency waves apparently do this more efficiently. https://en.wikipedia.org/wiki/Ground_wave#Radio_propagation https://en.wikipedia.org/wiki/Ground_wave#Radio_propagation (IANARE) Edit: It seems that diffraction around edges and electromagnetic ground waves are two quite different phenomena. (A third separate effect being a refractive index vertical gradient in the atmosphere causing diffraction, acting as a waveguide.) EM ground waves require that the ground is partially conductive, which the Earth is, but I suspect the Moon isn't particularly because it's dry. Still, diffraction will occur. Edit2: A better link for diffraction: https://en.wikipedia.org/wiki/Radio_propagation#Diffraction https://en.wikipedia.org/wiki/Radio_propagation#Diffraction "However, the angle cannot be too sharp or the signal will not diffract. ... Lower frequencies diffract around large smooth obstacles such as hills more easily."