Who writes and where do they get horoscopes?

Horoscopes are written by columnist astrologers, using a very general interpretation of the transits of the planets over a given chart. The basic idea is to take a given Sun sign and use it as the rising sign for a given chart. Thus if we take Taurus as an example, Taurus would be on the first house cusp. The rest of the signs would follow consecutively along the house cusps, ending with Aries on the 12th house cusp. The astrologer then takes a look at the current positions of the planets and places them according to their signs in the houses of the given chart. Interpreting these positions and the aspects they make, gives the astrologer a rough idea of the possible activities and situations that may arise for one with a certain Sun sign. The drawback to this type of forecasting is that the interpretations do no relate to the individual natal chart. If one has a different Sun sign from their ascendant, the same sign on two house cusps, or any other deviation from the textbook version of a Sun sign chart overlay the interpretation would be completely off. This is why many horoscopes are not valid for many people. In some cases looking up ones Sun sign can aid in achieving better results.