An Astronomical and Geometrical Analysis of the Star of Bethlehem Narrative (Matthew 2:1–12), in the Perspective of Kepler's Intuition

Preliminary noteThis manuscript constitutes the reference English version of a scientific preprint.Translated versions in French and Spanish may be made available subsequently.The English version shall be regarded as the authoritative version for academic citation. Abstract This paper presents an interdisciplinary analysis of the Star of Bethlehem narrative as recorded in the Gospel of Matthew (Matt. 2:1–12), examining Johannes Kepler’s hypothesis that the phenomenon may correspond to the great conjunction of Jupiter and Saturn in 7 BCE. The methodology is strictly rational and is based on a systematic confrontation between the ancient text and verifiable astronomical data, including planetary ephemerides, the geometry of the sky as observed from Judea, geographical constraints associated with the journey from Jerusalem to Bethlehem, and the historical chronology of the reign of Herod the Great. Each statement in Matthew’s account is treated as an independent constraint that must be simultaneously satisfied; failure of any single constraint would invalidate the model. The analysis shows that the Jupiter–Saturn conjunction of 7 BCE, remarkable for its triple occurrence and extended duration, exhibits an apparent motion compatible with the biblical descriptions of the star’s movement and stopping, including a well-defined planetary station, without invoking supernatural explanations. When realistic constraints on travel speed are introduced, a very narrow temporal window emerges. For a central and well-documented value of 6 km h⁻¹, the model uniquely selects 25 December 7 BCE. A finer analysis based on the same ephemerides further reveals an unexpected coherence at the hourly scale, with the timing of first visibility and meridian transit matching the duration of the terrestrial journey. This study does not aim to establish a historical event nor to support a religious belief. It demonstrates, rather, that Matthew’s narrative is astronomically, geometrically, and mathematically coherent, and cannot be dismissed as scientifically incompatible on purely rational grounds.