Black Moon or Lilith is part of Astro-psychology :it is the moonspot in your radix which is most distance from the earth. It means you can not wear any mask or find ways of protection , -also subconcious levels ,you are completely 'naked' there, so most vulnerable. (How to Find All the Lilith's(= Black moon) in Your Birth Chart AstroFix)
BLACK MOON LILITH ON THE MIDHEAVEN (mine is on the MC with a 1' orb in the 9H. Also, I have BML conjunct Pluto (exact!) conjunct Sun 10H in Libra (Venus in the 8H, very close to the 9H (orb=1)). What does that mean?! Career or social activities lead by my Pluto (regeneration/power), my BML (injustice/taking back my power) and Sun (will/vitality) energies to bring harmony/justice (Libra) through ideology/ethics (9H) and mysticism/bonding/"death" (8H)?!