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Let's go to Mars
c. 168 BCE

The Fire Star that Chinese astronomers could not pin down

A silk manuscript buried at Mawangdui gives working cycles for Jupiter, Saturn and Venus and none at all for Mars — the one planet that refused to keep a schedule.

A coarse black-and-white photograph of ink drawings on silk. Seven clear figures stand in a row: the leftmost is a small circle with four arms bent at right angles; the others are a bundle of curved strokes, a feathered spine, a stack of nested arcs, a Y on a long stem crossed by an X, a trident, and a long ribbed leaf shape. Most end at the bottom in a small open ring or crescent head, with the plume rising above it; the Y on the crossed stem ends instead in a small outlined triangle. A short column of Chinese characters runs beneath every figure.
A detail of the comet drawings in the silk sky-omen manuscript from Mawangdui tomb 3, each figure set above the short divination text that names it. It is a separate document from the Wuxingzhan and its planetary tables, recovered from the same tomb, which was closed in 168 BCE. · Image: China Arts, Volume 1st, Wen Wu Publishing, Beijing, China, 1979-10

In 1973, archaeologists opened tomb 3 at Mawangdui, near Changsha, sealed in 168 BCE. Among the grave goods was a silk manuscript of roughly 8,000 characters, the Wuxingzhan, "Prognostics of the Five Planets," with tables covering 246 BCE to 177 BCE. Most planets get a working cycle: twelve years for Jupiter, thirty for Saturn with a 377-day synodic period, an eight-year phase table for Venus running to the month and the lunar lodge — one of the twenty-eight segments Chinese astronomers divided the sky into. The Mars section survives and gives no period.

Chinese astronomers called Mars 熒惑, Yinghuo, which Christopher Cullen renders "Dazzling Deluder"; later usage settled on 火星, the Fire Star. The Huainanzi says its comings and goings are irregular, and a third-century text adds that no standard can be made from them. The Shiji's treatise on the celestial offices gives phase lengths that work out to a synodic period near 790 days, against a true mean of 779.94. No two Martian circuits take the same length of time.

The most feared configuration in Chinese astrology was 熒惑守心, Yinghuo shou Xin: Mars lingering in the lodge Xin, the "Heart", which contains Antares, a red star of nearly the same colour and brightness as Mars. Court astrologers read it as a threat to the ruler. In 7 BCE it was reported at the court of Emperor Cheng of Han. His counselor-in-chief, Zhai Fangjin, was sent wine and an ox by edict and killed himself that day, so that the disaster would fall on him, not the throne. The emperor died about a month later.

Huang Yi-Long recomputed the records. Of 23 entries for "Mars guards the Heart" in the dynastic histories, 17 describe events that never happened, 7 BCE among them; the real configuration occurs about once in eighty years. Huang reads the false entries as deliberate fabrication, while other accounts put most of them down to misdated records, "guarding" confused with a lesser approach, and Jupiter mistaken for Mars.