The legendary fourth-century total solar eclipse in Georgia: Fact or fantasy?

Abstract

In the early fourth century AD, a sudden return of daylight after a darkening of the sky purportedly swayed King Mirian of Georgia to convert to Christianity. Medieval written sources and modern geophysical models suggest that Mirian, whilst on a mountain top near the city of Mtskheta, may have observed a total solar eclipse (TSE). Adjusting for both visibility corrections and constraints on the accumulated clock error known as AT, we examine the local circumstances of the TSE of AD 6 May 319, which Gigolashvili et al. (Astronomical and Astrophysical Transactions 26, 199-201, 2007; Transdisciplinarity in Science and Religion 6, 217-221, 2009) recently proposed as the most likely natural explanation. If the basis for the legendary accounts of Mirian’s conversion is this TSE—but we make no judgment upon this question—then the value of AT inferred from written sources agrees well with generally-accepted values, such as those derived by Morrison and Stephenson (Journal for the History of Astronomy 35, 327-336, 2004), namely, (Formula presented.). We also show the extent to which this TSE would have seemed remarkable to observers at Mirian’s presumed location and less so to those nearby at lower elevations.