ज्योतिष

Jyotiṣa (ज्योतिष) comes from Sanskrit jyotis, meaning light, brightness, or the luminous heavenly bodies, combined with the suffix -a forming an adjective or field of knowledge. The root jyotis is Proto-Indo-European in origin, cognate with Latin lux, Greek leukos (bright), and Old English lēoht — all from *lewk-, to shine. Jyotiṣa is thus the science of light, the knowledge concerned with luminous things. But the original meaning was narrower and more specific than that phrase suggests: jyotiṣa was one of the six Vedāṅgas, the auxiliary disciplines required to correctly understand and perform the Vedas, and in this context it meant primarily the calculation of correct times for sacrificial rituals.

The Vedic ritual calendar required precise astronomical knowledge — the nakṣatras (lunar mansions, a system of 27 or 28 stations through which the moon passes in its monthly circuit) had to be correctly identified, the seasons had to be tracked, eclipses predicted, and the timing of the four great fire sacrifices coordinated with celestial events. The earliest jyotiṣa texts, the Vedāṅga Jyotiṣa, date to roughly 1200–1000 BCE and are concerned entirely with this ritual timekeeping. There is nothing in them of individual fate or birth charts; the stars serve the sacrifice, not the self.

The transformation of jyotiṣa into a system of individual natal astrology — what is now called Jyotiṣ or Vedic astrology — occurred through contact with Hellenistic Greek astrology, probably between the second century BCE and the fourth century CE. Greek ideas about the twelve-sign zodiac, the seven classical planets, and the twelve houses of the horoscope entered Indian astronomical thought and fused with the existing nakṣatra system to produce a hybrid that was neither purely Babylonian-Greek nor purely Vedic. The Sanskrit text Yavanajātaka (The Horoscopy of the Greeks), translated from Greek around 150–270 CE, marks the moment of formal synthesis.

Modern Jyotiṣ — taught in Indian universities, practiced by millions, and increasingly consulted by non-Indians seeking alternatives to Western astrology — retains the nakṣatra system as its distinctive feature, uses a sidereal zodiac (adjusted for the precession of the equinoxes, unlike most Western astrology which uses the tropical zodiac), and applies an elaborate system of planetary periods called daśā that has no Western counterpart. The word jyotiṣa, which began as a Vedic astronomer's calculation tool, now names one of the world's most widely practiced divinatory systems.