Science: In 1054 C.E., Chinese and Arab astronomers recorded the observation of a bright explosion in the sky. Now known to have been a supernova explosion, the remnant--the Crab nebula--still emits particles energized to extremely relativistic energies and radiates light at x-ray and gamma-ray wavelengths. In last week's Science magazine, a team of european astronomers report the discovery that the high-energy radiation (hard x-rays) from the Crab is polarized, yielding insights into the processes and mechanisms involved in making a dead star so active