Event #33: Tangle Star observed in China

The only ancient account of this comet appears in the Chinese text Han shu (100). It says a “tangle star” was seen in the southwest, “at about a distance of 20 degrees to the south of the Fang [β, δ, π, and ρ Scorpii]” on -146 August 6. The apparent location in the evening sky implies a UT of August 6.5. The Chinese describe it as “the size of a double-peck measure and was of a white colour.” The comet was seen northeast of Hsin [α, σ, and τ Scorpii] on August 7 and north of Wei [ε, ζ, η, θ, ι, κ, λ, and μ Scorpii] on the 8th. Estimates of the tail length on these two dates indicate values of 10 degrees and 60 degrees, respectively. The comet was seen near the Milky Way, north of Chi [γ, δ, ε, and η Sagittarii], on August 11. The comet became smaller until it “was as large as a peach” on August 16, after an appearance of 10 days.

J. Williams (1871) gave a slightly different interpretation. For August 6, he said the comet was “in the southern part of Fang” and that “when it left Fang it was 20 degrees in length.” For August 11, he wrote that the comet “entered Chi, to the north, near the star Han.” Han was identified as ζ Ophiuchi.

Ho Peng Yoke (1962) said the comet “went out of sight in the morning”; however, very similar parabolic orbits computed by S. Kanda (1973) and I. Hasegawa (1979) indicate the comet was in the evening sky, which indicates a probably UT of August 16.5.

Hasegawa’s orbit is given below and indicates the comet reached a minimum solar elongation of 18 degrees on June 15, and its most southerly declination of -24 degrees (apparent) on August 1. The comet reached a maximum solar elongation of 110 degrees on August 20.

Full moon: July 29, August 27

147 BC August 6 (P=June 28, d=0.15 on August 4); China. A white tangle star comet appeared in the southwest below Scorpius. On August 8 it was located north of Scorpius and its tail reached about 90 degrees. It left on August 16. Ho (32). Seneca records a comet after the death of Demetrius, king of Syria, and a little before the Greek Achaean war in 146 BE. It was described as large like the Sun, reddish like fire, and bright enough to dissipate the darkness. Barrett (19)

3rd year of the Zhongyuan reign period of Emperor Jing of the Han Dynasty, 6th month, day renxu [59]; a [white] fluffy star [pengxing] as big as a 2 peck measure appeared in the southwest, south of Fang [LM 4], at a distance of about 2 zhang. On day guihai [60], it was northeast of Xin [LM 5] and about 1 zhang long. On day jiazi [1], it was north of Wei [LM 6] and about 6 zhang long. On day dingmao [4], it was north of Ji [LM 7], near the Milky Way, and slightly smaller; by dawn when it left (i.e., was obscured in daylight), it was as big as a peach; by its departure on day renshen [9], [it had been visible] for 10 days in all.