Jyotisha (Sanskrit: ज्योतिष, IAST: Jyotiṣa), also transliterated Jyotiṣa or Jyotish, is one of the six Vedangas (auxiliary disciplines of the Vedas) historically concerned with observing astronomical bodies to determine correct timing for Vedic rituals.1) In contemporary usage the term most commonly refers to Hindu astrology, a system of predictive practice distinct from its historical, calendrical core; this shift in meaning is itself a point of contested framing addressed on jyotisha-astrology-skeptical-viewpoint and related pages. The earliest extant text on the subject, the Vedanga Jyotisha, deals exclusively with timekeeping and astronomical calculation, making no mention of horoscopy or prophecy.2)
As a field of historical and textual study, Jyotisha is examined by historians of science, Indologists, and Sanskritists primarily as a record of ancient Indian astronomical practice and lunisolar calendrics. The Vedanga Jyotisha, attributed to the sage Lagadha, survives in two recensions-one associated with the Rigveda (36 verses) and one with the Yajurveda (43-44 verses)-and describes a five-year yuga cycle structuring solar months, lunar months, and tithis for the purpose of scheduling Vedic rites.3) Scholars continue to debate the text's precise date, generally placed sometime in the second millennium BCE based on its internal astronomical references, though estimates vary and the matter is not fully settled.4)
Later texts, including the Siddhanta literature such as the Surya Siddhanta and works by astronomers such as Varahamihira, expanded Jyotisha into a more developed mathematical astronomy and, increasingly, into horoscopic astrology. The relationship between this later astrological development and Hellenistic astronomy and astrology is a matter of ongoing scholarly disagreement, addressed in jyotisha-greek-influence-debate. Separately, claims that Vedic-era Jyotisha texts encode a sophisticated heliocentric cosmology are addressed on Heliocentrism - Hindu Viewpoint.
In contemporary India, Jyotisha (in its astrological sense) retains an enduring institutional and cultural presence, including formal study programs at some universities, while remaining outside the scope of mainstream empirical astronomy.
There is broad consensus among historians of science that the Vedanga Jyotisha and related Vedic-era texts are concerned with calendrical timekeeping rather than predictive astrology, and that horoscopic astrology entered the Indian tradition through later developments. There is no scientific consensus supporting the predictive claims of astrological Jyotisha as practiced today; mainstream science classifies astrology, including Jyotisha, as a pseudoscience.5) See jyotisha-astrology-pseudoscience-consensus.