Planets do have frequencies. Their frequencies seem to be radio waves emitted because of the continuous variations of the electromagnetic field in the ionosphere of those massive celestial bodies.
It is not known any direct effect of radiowaves on humans.
I also like to listen to it sometimes because it remember me about infinite and untouchable beauty.
For the ancient world, the "music of the spheres" underlie the same concept for acoustic identity of the celestial bodies, although they were looking for cosmic harmony. They were searching for a palpable argument that cosmos is perfect in its wholeness.
The frequencies are there for real, but little we understand, so it makes the perfect field for metaphysical speculations.