 The term "Jyotisha" includes the study of astronomy, astrology and the science of timekeeping using the movements of astronomical bodies.It aimed to keep time, maintain calendar, and predict auspicious times for Vedic rituals.According to David Pingree, the field of timekeeping in Jyotisha may have been "derived from Mesopotamia during the Achaemenid period", but Yukio Ohashi considers this proposal as "definitely wrong".