Irish History From The Annals
In 1066 the Irish annalists recorded a precisely dated observation of Halley’s Comet.
The Irish annals not only recorded history and current events but also made important scientific and natural observations. For the year 1066 the Annals of the Four Masters record that a star as bright as the moon appeared on the Tuesday after Easter and was visible for four nights.
A star appeared on the seventh of the Calends of May, on Tuesday after Little Easter, than whose light the brilliance or light of the moon was not greater; and it was visible to all in this manner till the end of four nights afterwards.
The bright star was noted elsewhere in Europe and was depicted in the famous Bayeux Tapestry about a decade later. The significance of this precisely dated astronomical observation was not realized until 1705 when Edmond Halley published his Synopsis of the Astronomy of Comets. Halley had calculated that a comet that was observed in 1682 had the same orbit as one observed in 1607 and 1531. Realizing that the same comet was returning every 76 years he calculated that it would have previously appeared in 1066. We now know that the bright star recorded by the Irish annalists was in fact Halley’s Comet.
Depiction of Halley's Comet from the Bayeux Tapestry.