In 1066 AD, just after Harold Godwinson was crowned King of England, a comet was spotted in the sky, Zimmer writes in the book. Soon after, Godwinson was overthrown by the King of Normandy. The event was memorialized on a 224-foot-long cloth called the Bayeaux tapestry. "It would take astronomers over seven centuries to determine that the streaming star was in fact a comet - Halley's Comet, to be exact," Zimmer writes. "And so, in hindsight, we can now recognize the Bayeaux tapestry as a vital document in the history of science: the first depiction of these icy wanderers of the solar system."