Marduk, Zeus, and the Largest Planet

Jupiter is the largest planet in the solar system, more massive than all the others combined, and after Venus it is usually the brightest, which is why it was assigned to the chief god in more than one tradition: Marduk in Babylon, whose elevation over the other gods is the subject of the Enuma Elish; Zeus in Greece and Jupiter in Rome; Brihaspati in India, the guru or teacher of the gods, from which Indian astrology takes its reading of the planet as the significator of wisdom, priests and children. Its four large moons, seen by Galileo in 1610, were the first bodies observed to orbit something other than the Earth and were a decisive piece of evidence in the Copernican argument; the Great Red Spot, a storm larger than the Earth, has been observed for at least a century and a half and probably longer.

Jupiter's movements were tracked with particular care in the Babylonian omen series Enuma Anu Enlil and in the astronomical compendium MUL.APIN, both assembled from older material by around the first millennium BCE, centuries before the Hellenistic synthesis of roughly 100 BCE to 200 CE built the individual, chart-based astrology now practised; those Mesopotamian records already treated Jupiter's roughly twelve-year circuit as a marker of the reigning king's fortune and the state's stability, the same steady, benevolent character later transmitted through Greek Zeus and Roman Jupiter into the Hellenistic Greater Benefic and, further still, into Brihaspati's role as guru of the gods in Indian astrology. The line from a Mesopotamian omen for kings to a birth-chart signifier of personal wisdom and luck is a genuine transformation in what the planet was thought to say, not merely in the name attached to it.