This is the vital fluid emanated from any planet, which constitutes its basic coloring or quality, and is produced by a repetition within the planet of the same process which is undergone in connection with man and solar prana. The planet (the Earth, or any other planet) absorbs solar prana, assimilates, what is required, and radiates off that which is not essential to its well-being in the form of planetary radiation.
Planetary prana, therefore, is solar prana which has passed throughout the planet, has circulated through the planetary etheric body, has been transmitted to the dense physical planet, and has been cast off thence in the form of a radiation of the same essential character as solar prana, plus the individual and distinctive quality of the particular planet concerned. This again repeats the process undergone in the human body. The physical radiations of men differ according to the quality of their physical bodies. So it is with a planet.
Planetary emanative prana (as in the case of solar prana) is caught up and transmitted via a particular group of devas, called the "devas of the shadows," who are ethereal devas of a slightly violet hue. Their bodies are composed of the matter of one or other of the four ethers, and they focalize and concentrate the emanations of the planet, and of all forms upon the planet. They have a specially close connection with human beings owing to the fact of the essential resemblance of their bodily substance to man's etheric substance, and because they transmit to him the magnetism of "Mother Earth" as it is called.
(Extract taken from "A Treatise On Cosmic Fire" by Alice. A. Bailey)
