In 240 B.C.E., Chinese astronomers spotted Comet Halley in an observation that would become the earliest-known written record of Earth’s regular visitor. Writing in the Shiji chronicles a little more than a century later, Sima Qian reported: “In the seventh year of Emperor Qin Shihuang of the Warring States, a broom star first appeared in the east, then it appeared in the north.” Suggested dates for these appearances are rough: Twentieth century calculations estimate the first appearance was on or around March 30, while other appearances in the west may have been around late May/early June. Even earlier texts about Comet Halley have been suggested but not confirmed; regardless, the Chinese record would remain among the earliest written work about Comet Halley. Of course, since we now understand that Halley is a periodic comet that swings by Earth about every 76 years, many more would follow.
