The earliest datable observation of the aurora borealis

The Late Babylonian astronomical texts, discovered at the site of Babylon (32.5degreesN, 44.4degreesE) more than a century ago, contain what is probably the earliest reliable account of the aurora borealis. A clay tablet recording numerous celestial observations made by the official astronomers during the 37th year of King Nebuchadnezzar II (568/567 BC) describes an unusual "red glow" in the sky at night; the exact date of this observation corresponds to the night of 12/13 March in 567 BC. The most likely interpretation of the phenomenon is an auroral display. This event occurred several centuries before the first clearly identifiable observation of the aurora from elsewhere in the world, namely China in 193 BC. The Babylonian auroral observation is remarkable in the sense that it is one of a series of carefully recorded astronomical observations, for each of which the year, month and day are known precisely. This observation occurred at a time when the geomagnetic (dipole) latitude of Babylon was about 41degreesN compared with the present value of 27.5degreesN, suggesting a higher auroral incidence at Babylon in 567 BC than at present