Keun Nan Mun

Keun Nan Mun is a nineteenth-century western romanisation of a Chinese asterism name, of the kind that entered European star lists through Jesuit reports of Chinese astronomy and then through the compilations that drew on them. Romanisations of this period predate both Wade-Giles and pinyin and are not consistent from one book to the next, which is why such names are often difficult to match confidently to a modern Chinese designation, and why the same star can appear under several spellings in different lists. What can be said with confidence is that the name belongs to the Chinese rather than the Graeco-Arabic layer of star nomenclature, and that the star it labels is a minor member of the figure of Andromeda. No traditional planetary nature is recorded for it, and it plays no part in the interpretive tradition.

The Chinese asterism it likely renders belongs to one of the twenty-eight lunar mansions of Chinese astronomy, the xiu, whose stars were grouped into small named asterisms quite differently from the Greek figures laid over the same sky; a name surviving only as a garbled nineteenth-century romanisation, unmatched to any secure modern Chinese source, is a fair illustration of how much of that independent tradition reached Western star lists only in damaged, third-hand form.

The atlas records this star at Taurus 6 degrees 25 minutes, projected onto the ecliptic from a position in Andromeda, a constellation that lies well north of the ecliptic and none of whose stars is ever seen among the zodiacal figures.

Precession makes that longitude a dated quantity. A fixed star advances about fifty seconds of arc a year in tropical longitude, a degree in roughly seventy two years. Taking the recorded figure for epoch 2000 and applying a uniform rate, the star entered Taurus around the middle of the sixteenth century and will not reach Gemini for another sixteen or seventeen centuries. It has been in the sign for a shorter span than most of the entries around it.

The dating is worth setting beside the name. This entry preserves an old romanisation of a Chinese asterism name, and Chinese sky-lore divided the heavens on an entirely different plan from either the Greek constellations or the zodiacal signs, using circumpolar palaces and equatorial lodges rather than a band along the ecliptic. A Chinese name attached to a tropical zodiacal longitude is therefore two systems joined by a later compiler, not a fact drawn from either.

None of that makes the number wrong. It makes it a projection twice over: a star north of the ecliptic assigned an ecliptic longitude, under a name from a tradition that did not use one.