Babylonian Zodiac

If any system here deserves to be called the origin, it is this one. The zodiac you know — twelve signs, each a thirtieth of the sky — was invented in Babylon, and almost every other zodiac on this site, the Western one above all, descends from it. Babylonian sky-watching was old, careful and written down: for well over a thousand years priests recorded the movements of the Moon, Sun and planets on clay tablets.

The great early record is MUL.APIN, a compendium of Babylonian astronomy compiled by around 1000 BC. It already lists the constellations lying along the path of the Moon — eighteen of them, the direct ancestors of the twelve zodiac signs, including the Bull, the Lion, the Scorpion and the rest. But these were still uneven constellations, marking regions of sky, not the neat mathematical scheme that would follow.

That scheme is Babylon's real invention. In the second half of the fifth century BC, Babylonian astronomers did something new: they divided the ecliptic — the Sun's yearly path — into exactly twelve equal signs of thirty degrees each. This was the zodiac proper: no longer ragged star-pictures but a precise coordinate system for tracking the planets. It is one of the quiet milestones in the history of science.

From there it travelled. Babylonian astronomy passed to the Greeks, who added the horoscope and the personality lore; from the Greeks it reached Rome, India and eventually the whole world. So when this atlas says a system was "adopted from the West," or "descended from Babylon," this is the Babylon it means. The honest verdict is simple and, for once, grand: this is the real thing, and the parent of most of the rest.