Astronomical/Astrological symbols for other planets' moons
Astronomical/Astrological symbols for other planets' moons
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There are astronomical symbols for each of the 9 planets in our solar system, as well as for the Sun, the Moon, and some of the asteroids.  However, I have  not been able to find any symbols for the moons/satellites of other planets.
Astronomers, as far as I can tell, use the symbol of the planet plus a roman numeral indicating which orbit the moon is in.  This is all well and good, but not very interesting or evocative.  Astrologers, on the other hand, have no real reason to have separate symbols for the moons, since they are always in effectively the same part of the sky as their planet (when seen from Earth).
As someone who enjoys thinking about possible lifestyles of the future,  I imagine a time when the outer planets will be inhabited, or at least have astrologically interesting events happening on them.  (I'm not a believer in astrology myself, but find it interesting.)  Future astronomers and astrologers may wish to have symbols for the moons of the planet they are inhabiting  or orbiting.
I have invented symbols for many of the other moons.  My general method is to take some aspect of the planetary symbol and apply it to symbols differentiating the moons, usually the initial of the moon's name in the appropriate writing system.  I offer these symbols up to the public domain, for use by future astronomers, future astrologers, and anyone else who's interested.
Mars
Mars has two moons, Phobos and Deimos.  The symbols for them are based on the lower-case versions of the Greek letters Phi and Delta, which begin those two names in the original Greek, with the arrow from Mars's symbol added on.
Phobos
Deimos
The Jovian planets
The Jovian gas giants each have a large number of moons (at least 13 for Neptune, at least 63 for Jupiter).  It's not really feasible to include them all, but some are larger than others.  I've chosen an admittedly arbitrary threshold of 10 Zg (1019 kg) and created symbols for any moon larger than that, which lets in Saturn's moon Hyperion but not Jupiter's  largest non-Galilean moon Amalthea.  This is also near the point at which moons become non-spherical - there are some non-spherical objects above this line, but no spherical ones below.
Jupiter
Jupiter has four "large" moons - the four Galilean moons.  For their  symbols, the Greek letter beginning their names is combined with the cross at  the bottom of the symbol for Jupiter.
Io
Oberon
Neptune
Neptune has 3 "major" moons - Triton, which is the 7th largest moon in the Solar system, and the non-spherical Nereid (31 Zg) and Proteus (50 Zg). Their symbols combine the Greek letter beginning their names and Neptune's trident.
Proteus
Nereid
The dwarf planets and large TNOs
There are five currently-recognized dwarf planets, three of which are known to have moons.  (This is not entirely a coincidence - the presence of moons helps determine mass, which is part of the classification process.)   Pluto and Ceres have traditional symbols, and I suggest symbols for Eris, Makemake, and Haumea on my page of symbols for TNOs .   There are also a number of large TNOs that are likely to be eventually classified as dwarves, two of which are known to have moons.  I have proposed symbols for many of these as well, on that same page. I have designed symbols for all the dwarf planets' and TNOs' moons, based on the traditional symbol or my suggested one.
Pluto
Pluto has two symbols, one usually used by astronomers and one  usually used by astrologers.  The astronomical symbol is a combination of the  letters P and L, both for the planet PLuto and in honor of Percival Lowell.  The astrological symbol is a circle inside an arc above a cross.
Pluto has five moons: Charon, Nix, Hydra, Kerberos, and Styx. Charon was discovered  by James Christy and named to honor his wife Charlene, so a symbol combining  C and H is the obvious choice for an astronomical symbol. The astrological  symbol uses the floating circle from Pluto and applies it to a sideways  crescent, referencing both  Charon being a moon and Charon's mythological meaning as a boatman across  the river of the dead. (A version of this symbol is apparently already a  less common symbol for Pluto.)  Nix is either a misspelling of the Greek goddess Nyx, in which case it starts with Nu, or Latin for "snow", which  starts with N.  Luckily capital Nu and capital N look the same.  Hydra begins with Upsilon in Greek.  Kerberos and Styx have straightforward symbols involving Kappa and a lowercase Sigma.
Charon (astronomical)