Origin of the Earth--Moon System from the Jovian Disruption of Tiamat: A Unified Model for Venus, the Asteroid Belt, and the Galilean Satellites

In Babylonian myth, Marduk slays Tiamat and splits her body into heaven and earth. This paper shows that a real version of this cosmic cataclysm may have created our Earth–Moon system. We propose that a ~0.5 Earth‑mass differentiated embryo — Tiamat — accreted at 2–3 au and was tidally disrupted by Jupiter (the real Marduk) during the Grand Tack migration. From this single disruption emerged the main fragments that became Earth and the Moon — they are thus isotopically identical by birth, solving the long‑standing isotopic crisis without fine‑tuning. A third fragment, Theia (the “arrow” of Marduk), was also produced. Theia struck the Earth–Moon system later, delivering the missing angular momentum that set Earth’s obliquity to 23.44°. In this framework, Theia is not an ad hoc assumption but a derived consequence of the angular momentum budget. Two independent N‑body proofs establish the physical necessity of the Grand Tack: 1. Earth‑crossing efficiency depends entirely on Jupiter’s position: 0.58% at 5.2 au, rising 60‑fold to 31.25% at 2.0 au with Saturn. Jupiter must have migrated inward — the Grand Tack is not optional. 2. Angular momentum analysis of 466 Earth‑crossing fragments gives a predicted obliquity of only 0.77°, 30 times smaller than Earth’s actual 23.44°. This deficit proves that a single late impactor — Theia — must exist. The model simultaneously explains nine independent observations: iron depletion, oxygen and chromium isotopic identity, volatile depletion, the Galilean satellites’ density gradient, Venus’ slow retrograde rotation, Jupiter’s heavy element enrichment, the asteroid belt’s origin, and Theia’s derived origin. Six falsifiable predictions are presented for Europa Clipper, JUICE, and future missions. Thus, the ancient myth finds a quantitative echo: Earth, Moon, and Theia are all children of Tiamat’s destruction by Jupiter.