The question
Why did people start reading the sky for meaning?
The short answer
Babylonian scholars watched the sky to warn kings of what the gods intended. Their careful records became the foundations of both astronomy and astrology, which were not separate subjects for most of history.
What science knows
Historical FactThe omen series Enūma Anu Enlil collected thousands of celestial omens on some 70 tablets: if the moon does this, that will happen to the king or the land. Astrology began as state divination, not personal horoscopes.
From 652 BCE, Babylonian scholars kept “astronomical diaries”, nightly records of the sky, weather and prices, for centuries. The oldest known personal horoscope, on a cuneiform tablet, dates to 410 BCE.
The pattern
Established ScienceThe diaries’ long records let Babylonian astronomers find cycles precise enough to predict lunar eclipses, including the 18-year Saros cycle.
What is still uncertain
Mixed EvidenceHow and when Babylonian methods passed to Greek and Egyptian astrologers in the Hellenistic period is still being reconstructed from fragmentary texts.
Why humans find it interesting
Historical FactIn the 2nd century CE, Claudius Ptolemy wrote both the Almagest, a foundation of astronomy, and the Tetrabiblos, a foundation of Western astrology. To him they were two halves of one study of the heavens.
CUE perspective
CUE PerspectiveAstrology began as careful observation of real cycles, joined to interpretation. The observation became astronomy; the interpretation became astrology.
CUE sits on the interpretation side, and knowing that history keeps it honest about which is which.