“Synastry” refers to the astrological study of relationships. There are several techniques. Each have their own merits.
A synastry chart or “chart comparison” is when you check how one person’s planets relate to another person’s and interpret what you find.
As an example, people who have their Jupiter conjunct one of your personal planets are almost always benevolent towards you. In return, your energy will buoy them.
In another case, a person’s Mars may square your Sun. They may attack (Mars) your ego (Sun). They may also just fire you up.
You have to be careful when judging these things. Synastry will show that there is an interaction between two people. How the interaction plays will depend on the choices the people make.
A composite chart is a chart of the midpoints between two charts. Say again?
The mathematical midpoint between the two Suns becomes the composite Sun. The midpoint between the two Moon becomes the composite Moon and so forth.
What you’re doing is merging the two charts, to come up with a chart of their relationship. This may sound squirrelly but these charts are valid. They most definitely work!
The difference is that the one method (comparison) shows you how two people interact and affect each other. The other (composite) gives information about the relationship itself. It tells it’s purpose and it’s qualities. Is the union happy? Stable? Erratic?
Two people can feel really good around each other but still have a relationship that is erratic and fraught with difficulty or impediment of some kind.
Also, the composite chart is meaningless unless the relationship actually forms. It’s a hypothetical. If you see someone you like and you see that you have a nice composite chart with that person, it won’t matter unless you merge with them in some way. It is at that point, the composite chart comes into being.
You can also have two people with very difficult charts. But when you put them together their composite is great.
This would be a situation where people are better together than apart. You see it in life when someone says, “My life was crap, but then I met….”
Which synastry technique do you prefer?