Babylonian Astronomy

The astronomical tradition of ancient Mesopotamia — the first civilization known to possess a functional planetary theory, and the foundation upon which Greek, Islamic, and modern astronomy were built.

Relevant to crossing-mercury-hermes as the earliest documented source of the Mercury-as-messenger association, predating and independent of the Greek Hermes tradition.

What Made It Distinctive

Babylonian astronomers developed a systematic empirical approach during the 8th–7th centuries BC — recording observations with internal consistency and using them to make predictions. Their base-60 (sexagesimal) number system simplified calculation of large and small numbers.

The "first successful attempt at giving a refined mathematical description of astronomical phenomena" — and "all subsequent varieties of scientific astronomy, in the Hellenistic world, in India, in Islam, and in the West ... depend upon Babylonian astronomy in decisive and fundamental ways."

They separated observation from cosmology: where Greek astronomers imposed geometric models (circles, spheres), Babylonians used purely arithmetical procedures to predict where planets would be — without needing a physical theory of *why*. This empirical pragmatism was in some ways more scientifically honest.

By 350–50 BC, some Chaldean astronomers had even begun using geometric methods in abstract mathematical space to describe Jupiter's motion — prefiguring the Oxford Calculators by 1,500 years.

Key Texts and Instruments

MUL.APIN (~7th century BC, but content far older) — catalogues of stars and constellations; schemes for predicting heliacal risings/settings of planets; lengths of daylight measured by water clock and gnomon. Calls Mercury "the jumping planet" (UDU.IDIM.GU₄.UD).

Venus tablet of Ammisaduqa — 7th-century BC copy of observations probably dating to the 2nd millennium BC; the oldest surviving planetary astronomical text.

Enuma Anu Enlil — series of cuneiform tablets cataloguing sky omens; eclipses considered most dangerous; Mercury, Venus, and Jupiter movements used as omens.

Astronomical diaries — systematic nightly records allowing identification of repeating cycles, including the Saros cycle (18-year eclipse cycle).

Mercury in Babylonian Astronomy

Mercury was tracked from at least the 14th century BC (MUL.APIN). The Babylonians called it Nabu — the messenger to the gods in Babylonian mythology. This is the same archetype as the Greek Hermes, arrived at independently by a civilization that had limited contact with Greece.

The parallel: Babylonians observed Mercury's behavior (never far from the Sun, appearing near every part of the horizon over time, fast and erratic in its movements) and named it after their messenger deity. Greeks observed the same planet and independently named it after their messenger deity. Two cultures, one orbital truth.

This is central to the argument in crossing-mercury-hermes that the messenger characterisation, though mythological, captured something real about Mercury's orbital nature.

What the Babylonians Knew About Mercury's Proximity

The Babylonians could observe Mercury's maximum elongation (~28° from the Sun) and its rapid synodic period (~116 days). They would have known Mercury was always "near" the Sun in the sky. What they could *not* know — and what wasn't formalised until 2019 — was that this Sun-proximity made Mercury statistically closest to all other planets. That insight required understanding heliocentric orbital geometry, which even the most advanced Babylonian astronomers did not possess (their one surviving heliocentric model came from Seleucus of Seleucia, ~190 BC, after substantial Greek influence).

The messenger association was thus based on *observable behaviour* (erratic, fast, always near the solar hub of the planetary system) rather than on the proximity insight — making the 2019 discovery even more striking as an accidental confirmation.