The First Known Observation Took Place In 239 B.C.
According to the European Space Agency, the first known observation of Halley’s Comet dates back to 239 B.C. and was by Chinese astronomers. They recorded the comet’s passage around Earth in the Shih Chi and Wen Hsien Thung Khao chronicles.
The comet returned in 164 B.C. and 87 B.C., which makes historians believe that Halley is also mentioned in the Babylonian clay tablet records now housed at the British Museum in London. A Nature research paper noted, “These texts have [an] important bearing on the orbital motion of the comet in the ancient past.”