I think they might as well be related.
But I've only read half an alchemy book a long time ago so I don't remember much.
Sun rules gold, Moon rules silver, Mercury rules Mercury (?), Mars rules iron (?)... and I'm lost.
Maaan, I used to have all that in a notebook. But the notebook ain't here. Like... each alchemical process (coagulation, etc, etc.) is related to a particular sign. Virgo was purification, for example (if that was the name of the process).
Also each process corresponds to a chakra and each chakra is ruled by a planet.
Like the last process (and I really don't remember the names) is represented by 7th chakra and is ruled by the Sun. The last but one is represented by 6th chakra and is ruled by the Moon. The process before that - 5th chakra - Mercury, 4th chakra Jupiter, 3rd chakra Mars, 2nd chakra Venus, 1st chakra Saturn. That's what I remember.
Then according to Manly P. Hall, for example, each planet represents a challenge we must handle in order to stop the process of reincarnation and return home. Moon - parting with our illusions, Mercury - getting over the need to over-intellectualise, Venus - compassion instead of passionate love, Sun - existing without the need for energy and Mars... I forgot. The idea is when you handle all those you go to the gatekeeper (Saturn) who judges you on how well you've mastered them. Uranus, Neptune and Pluto represent things beyond ordinary human awareness.
I think alchemy is quite useful as each process signifies a stage in the development of your psyche, a real spiritual guide. What I remember is that first you had to burn your own ego, then immerse what is left into water and precipitate, than you work on what is left, there was some integration of opposites, etc. I think it's a real spiritual guide and not to be taken literally but quite symbolically.
Not a very coherent narrative but you reminded to have a look at those once again. Thank you and the universe for that.