What does it mean to see or be shocked by a comet nine years later?

Nine years later, a comet appeared, covering almost the whole sky. According to the query poetry network, nine years later, comets came from historical records. This sentence describes the year and scale of the comet, which may have astronomical or divination significance. I hope a comet will appear nine years later, covering almost the whole sky. Historical Records is the first biographical general history in the history of China, written by Sima Qian, a historian of the Western Han Dynasty.