Modeling of solar and interplanetary magnetic fields

A brief historical review of solar and interplanetary magnetic field modeling and analysis is presented. The modeling was initiated with the routine observation of longitudinal magnetograms and the application of current free potential magnetic fields for its interpretation. Almost simultaneously, the development of detailed Her observation motivated the constant-alpha, force-free magnetic field analysis. Subsequent development of transverse magnetograms leads not only to further refinements of the analysis and modeling but also to many physically meaningful interpretations of the observations. In this review, historical development is traced with the emphasis placed on the yet unanswered questions.