Below is the noon chart of a person born in 1957. Between 1977 and 1991 the person had a major operation. Can you deduce using transits, solar arcs, or your program's dynamic biwheel function, what the operation was for? Advanced astrologer's might deduce the operation immediately by just looking at the chart.
The asteroid shown trine Sun is Arachne known for weaving plots, entanglements. The asteroid does not determine what the operation was, just the fact that this person was evil and was always involved in plots, entanglements.