Weird stuff seems to go with major comets. When a comet appeared in A.D. 60, the people of Rome assumed it meant the impending death of their still new emperor, Nero. He responded by exiling a potential rival. When another comet turned up just 4 years later, ancient historians say he ordered the execution of dozens of nobles. It is said that Moctezuma II saw a comet in 1517 that foreshadowed the downfall of Aztec empire. In 1910, a wave of hysteria swept over the United States amid reports that Earth was about to pass through Halley's tail.