can anyone explain the importance of the moon in western astrology?

The moon used to be considered more significant then the sun sign.

The moon relates to emotions and intuition. Also feminine and mother aspects and relations.

What I know from palmistry is the moon relates to sub-conscious creativity, dreaming, imagination...

"Keywords:
instincts, subconscious, private life, emotions, past lives, mother, intimate self"

- http://astrology.about.com/od/foundations/p/MoonSign.htm

Sun, Moon and Asc are the three most important things in astrological natal chart..

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What about the rising sign. I understand the rising sign to be quite significant too.[/url]

Basic astrology
Now basically your sun sign is your 'core beliefs, values, ego' and Asc is your physical body, mode of expression and mask and persona that we all wear and hide behind, but definitely not what's going on underneath. What's going on underneath is your Sun sign. Moon sign, house placements and aspects describe your emotional and intuitive responses, also describes your view of your mother, as saturn describes your father by sign and house position.

So, think of a glass milk bottle the bottle is your Asc and your sun the milk, but the milk still has to 'come out' through the glass neck of the milk bottle....

Now aspects within a natal chart represent 'facets' of our personality, because we are all multifaceted beings. What these do is 'break down and compartmentalise' these facets into smaller bite size chunks. This does take quite a lot of self analysis and objectivity to 'see yourself' and why you do certain things and behave in certain ways. Actually it can be quite good therapy...

Remember back to your school days an opposition is 180', square 90', trine 120', and sextile 60' Now challenged aspects are conj (depending on the planets, cos some like each other and some really don't) squares and oppositions. Easy aspects are conj (if the planets get along) eg: Jupiter conj Moon, sextile and trine. Quincunx is inbetween (depending on the planets) causes health strains and unresolved or hard to balance planets/energies.