Two Comets

This is a brushed-up version of a talk I made at the AIP Kafferunde, 28.02.08. It connects an event that happened to Halley's comet, to an image in the thousand-year-old Bayeux Tapestry.

Bayeux Tapestry
Tapisserie de Bayeux

Really an embroidery, 50 cm × 70 m

It is the story of the Norman conquest of England in 1066 by the Norman prince William the Conqueror (Guillaume le Conquérant).

This was an important event, in fact. It's the reason the text you are reading consists largely of French and Latin words, rather than being mostly of Germanic origin. The Normans spoke Old French, and after the conquest, they imposed that language on all parts of courtly, professional, and religious society.

The king of England, Harold Godwinson, was coronated in 1064.

Harold had been on a campaign with William in Normandy some years earlier. So Harold and William were personally very well acquainted.

The year before the Norman invasion Harold had been fighting his brother Tosting who had allied with king Harald of Norway to take the throne from him.

Harold was killed in the invasion, and England was overrun by the Normans.

The story of the tapestry is well known. The tapestry was commissioned for political reasons, specifically to extol the conquest. But the workers would have been English.

An important point is that the people who made the tapestry were personally present to see some of the happenings, and they were careful in many details. In fact, this tapestry is the world's biggest and best depiction of medieval dress and military equipment.

For example, the Norman men shaved the back of their heads, while the Anglo-Saxons had mustaches.

But an otherworldly event is also depicted in the tapestry. Halley's comet would have appeared on 24 April, nearly four months after Harold's coronation. The people thought it bode ill. It certainly seemed to have worked no good for Harold.

But again, the weavers of the tapestry saw it with their own eyes. Yet their depiction seems quite fanciful... a star thing with something like an umbrella behind it, with multiple trails.

Comet Holmes (2007)

Comet Holmes experiences an "event"

Photo by Ivan Eder (Nov 4 2007)

Within a matter of a few hours, the apparent head of the comet swole to the size of the planet Jupiter, and developed distinct trails. The modern explanation is that, probably due to the sun's heat, and explosion occured on the surface of the comet, blowing out a large quantity of gas and dust, that in turn was illuminated by the sun.

Compare with Hally's comet in the tapestry

I think the depiction of Hally's comet is not so fanciful after all. I suspect that the weavers of the tapestry witnessed Halley's comet having an "event".