In the Middle Ages and Renaissance, Latin was the international language of scholars in Europe, and most people who wrote about learned topics wrote in Latin and used Latinized versions of their names on their writings. Sometimes they'd use a Latin-sounding name that was phonetically similar (such as Kopernik->Copernicus); other times they'd construct a Latin equivalent that was etymologically related.

So most of the philosophers, alchemists and so forth of the age, including the medieval Arab writers on astronomy and medicine, are still often known by pseudo-Latin versions of their names.