An evaluation of astronomical observations in the Irish annals

The astronomical entries scattered through the Irish annals have been examined in a serious astronomical context by R. R. Newton as part of his research into the accelerations of the earth and moon, and by D. Schove and A. Fletcher, as part of the Spectrum of Time project. They have never, however, been fully collated and examined as a whole as this paper undertakes to do. What emerges is a body of records from 442 to 1133 documenting eclipses, comets, aurorae, volcanic dust clouds and possibly a supernova; from 664 to 1133 all of these records are of observations made in or near Ireland, and most of them are accurate in their chronological and descriptive details. Analysis of the details of these records implies that, at least from the seventh to the eleventh centuries, careful and sustained observation and recording of astronomical phenomena were conducted in some Irish monasteries and it is clear that the underlying motive was religious and specifically eschatological, i.e. to detect the first signs of the end of time as prognosticated in the Book of Revelation. Critical examination of this data allows us to throw new light on the circumstances of the Synod of Whitby in 664, to identify the date of the eruption of the volcano Eldgjá in Iceland as the springtime of 939 and to identify a possible Western observation of the supernova of 1054.