Event #639: A sparkling star comet is seen in Virgo, and thought to presage the death of the Roman emperor Jovian

AD 363 Aug 26-Sep 23 [China] (Ho 173)

(a) 1st year of the Xingning reign period of Emperor Ai of the Jin Dynasty, 8th month; a star became fuzzy in Dajiao and Kang [LM 2] then entered Tianshi.

[Song shu: tianwen zhi] ch. 24

(b) 1st year of the Xingning reign period of Emperor Ai of the Jin Dynasty, 8th month; a star became fuzzy in Jiao [LM 1] and Kang [LM 2] then entered Tianshi.

[Jin shu: Ai di ji] ch. 8 [Jin shu: tianwen zhi] ch. 13

363 August-September; China.

A bushy star comet was seen in Virgo. A contemporary Roman historian records a comet presaging the death of the Roman emperor Jovian who died in February 364.

Ho (173), Barrett (55)

The Chinese text Chin shu (635) says a “sparkling star” was seen sometime during the month of 363 August 26 to September 23. The object appeared at Chio [α and ζ Virginis] and Khang [ι, κ, λ, and φ Virginis] and entered the T’ien-Shih Enclosure [Hercules, Serpens, Ophiuchus, and Aquila]. The comet would have been in the evening sky. The sun would have been only 2° from Virginis on September 23.

The Roman historian Ammianus Marcellinus wrote Rerum Gestarum around 395. In his discussion of events occurring in 363 he wrote, “… in broad daylight comets were seen, about which the views of those versed in natural history are at variance.” He continued with a narrative on what comets might be by writing, “For some think that they are so called because they are numerous stars united in one body, and send out writhing fires resembling hair. Others believe that they take fire from the dryer exhalations of the earth, which gradually rise higher. Others again think that the rays streaming from the sun are prevented by the interposition of a heavier cloud from going downward, and when the brightness is suffused through the thick substance, it presents to men’s eyes a kind of star-spangled light. Yet others have formed the opinion that this phenomenon occurs when an unusually high cloud is lit up by the nearness of the eternal fires, or at any rate, that comets are stars like the rest, the appointed times of whose rising and setting are not understood by human minds.” The comet was believed to be one of the portents of the death of the Roman emperor Jovian, who died on 364 February 17.

Based on the apparent path alone, I. Hasegawa (1979) suggested this might be a previous apparition of comet Bennett (C/1969 Y1), with a likely perihelion date of 363 September 15±10, while the period between this apparition and that of 1970 was 1605 years. According to computations by B.G. Marsden, Zdenek Sekanina, and D.K. Yeomans in 1973, the “original” orbit of comet C/1969 Y1 had a period of 1579 years.

Full moon: August 11

Sources: Chin shu (635), p. 241; A.G. Pingré (1783), pp. 302, 597; J. Williams (1871), p. 28; Ammianus Marcellinus, translated by John C. Rolfe, Cambridge: Harvard University Press (1956), book 25, section 10; Ho Peng Yoke (1962), p. 159; AJ, 78 (1973 Mar.), pp. 219, 221; A.A. Barrett (1978), pp. 103-4; I. Hasegawa (1979), pp. 263-4.