But if you know where to look they can certainly be found. Before 1950 very few scientific studies of astrology existed. The result was a notable increase in the number of critical studies. It took seven person-years to prepare, surveyed many hundreds of books and articles, and documented over 150 empirical studies published in astrology journals and over twenty published in psychology journals. By then the advent of home computers in the late 1970s had revolutionized astrological practice and research.
Today there is a scholarly research base that covers most of the basic claims of astrology.
Unfortunately, much of this work is neither widely known nor easily accessible, a point I will return to shortly. The 'Mars effect' is specifically addressed by Benski et al. The recent, scholarly journal Culture and Cosmos under the editorship of Nick Campion is an important contribution to the history of astrology across the world. Since the mid-1970s, psychology journals have averaged a steady total per year of about two empirical studies of astrological claims, plus an equal number devoted to related topics such as the acceptance of astrological statements or the prevalence of belief in astrology, all of them easily accessible via PsycLIT, the American Psychological Association's computerized abstract database. Fortunately most of the major reviews listed above cover this wider information base.