Comets have been known since ancient times

• known to ancient Greeks and Romans as "bearded stars"

• recorded on many ancient Chinese star charts, known as "broom stars"

Comets were generally taken to be a sign of the times...

at one decade per major comet, generally portended as some kind of omen

Harold, newly crowned Anglo-Saxon King of England, has major issues with his Norman neighbors - William, Duke of Normandy

Comet appeared in the sky, and England was conquered by William culminating in the Battle of Hastings in 1066.

Not all bad, though, since William is responsible for the modernization of England and laying the groundwork for important things like the Magna Carta in 1215.