Great Comet of 371 BC
The Great Comet of 372–371 BC was a comet that was observed by Aristotle, Ephorus, and Callisthenes. Ephorus reported that it split into two pieces, a larger fragment that is thought to have possibly returned in 1106 AD, as X/1106 C1, and another smaller fragment. While visible from Earth, it was said to have cast shadows at night comparable to a full moon. The Great Comet is thought to possibly be the source of the Kreutz sungrazer family.
Observations
The comet was reported to have had a long, bright tail that had a reddish colour, as well as a nucleus brighter than any star in the night sky.Aristotle wrote in Book 1 of Meteorologica
Quoting a lost source, Diodorus Siculus wrote that
Effect on prophecy
Diodorus wrote that the comet was believed by some to have foretold the decline of the Spartans, and describes the debate over its nature.Dispute over date
The comet is sometimes referred to as occurring during 373-372 BC instead of 372-371 BC. Seneca wrote later that the sightings of the comet coincided with the destruction of Buris and Helice, suggesting a date of 373-372 BC.Most sources refer to it as occurring in 372-371 BC. Göran Henriksson writes:
Relation to other comets
Heinrich Kreutz was a German astronomer who claimed that the orbits of several sungrazing comets were related and likely produced when a large Sun-grazing comet fragmented hundreds of years previously. That group, known as the Kreutz Sungrazers, has produced some of the brightest comets ever observed, including X/1106 C1 and Comet Ikeya–Seki. Aristotle's comet may have been the progenitor of the entire group. If it was the source of all Kreutz sungrazers, it must have had a nucleus of at least 120 km in diameter.It has been speculated that the comet was Comet Encke, although this is not widely accepted.