The poet and the almanac

(appeared in May 2016)

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A feature of the night sky referred to in an ancient poem may help fix the date the poem was written, says S.Ananthanarayanan.

Mention of well known astronomical phenomena in ancient records has helped fix the date of the records, or, alternately, the date of the event. Even records of the going and coming of ships at ports and the cargo handled has helped determine the dates of harvests or even periods of droughts or floods, which, in turn, has helped fix the date of other happenings in ancient times. The record of eclipses in ancient lore has similarly helped date event associated with the eclipse. An eclipse being seen at a place different from what was expected has even helped detect changes in the speed of rotation of the earth, and hence possible variations in sea levels!

Manfred Cuntz and Levant Gurdemir from the University of Texas at Arlington and Martin George from the National Astronomical Research Institute of Thailand, Chiang Ma, and University of Southern Queensland, Australia, describe in the Journal of Astronomical History and Heritage, their work of fixing the time of year of a celebrated poem by Sappho, a Greek woman lyric poet, with the help of information about setting of a star formation in the night sky, which the poet uses as an image of abandonment that she feels.

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Sappho was from the city of Lesbos, a Greek island in the Aegean Sea and was among the greatest of lyric poets of antiquity. She is believed, based on various writings and also some of her own, to have lived in the seventh and sixth centuries BCE (630 – 570 BCE). Most of her work, which was collected into nine volumes by the Library of Alexandria (3rd century to 30 BCE), however, has been lost and only scraps remain. But what remains is still a major corpus and has been widely acclaimed. “…..the skill with which she placed her vowels and consonants, ……is evidenced by almost any stanza; the music to which she sang them has gone, but the spoken sounds may still enchant,” says noted translator and editor, David A Campbell. “Her images are sharp—the sparrows that draw Aphrodite's chariot, the full moon in a starry sky, the solitary red apple at the tree-top…..” Campbell goes on to say.

Her use of symbols of the moon and the stars, the sun and planets is seen in many places in her work and the example that the authors of the paper in the Journal of Astronomical History and Heritage took up, is a poem, fragment No. 52, known as the Midnight Poem, which goes:

The verse makes three observations of the sky and then of her own isolation as time goes by. The physical image is that while it is midnight, the moon has set and so has Pleiades, an important cluster of stars that is visible in the Northern hemisphere. From the fact that Pleiades has set just at midnight, we can work out the time of the year the lines may have been written.

Pleiades

Pleiades, also known as Seven Sisters and denoted as Messier 45 or M 45, is a bright formation of six main stars, which can be seen for most of the night during the winter months. The position of the group in the sky is in the constellation, Taurus, and towards Pisces (it is most easily located in the sky by first tracing the three bright stars that form the ‘belt of Orion and then following the stars to the west about eight times the length of the belt). The position within Taurus places the cluster in line with the sun, and hence not visible, during April-May, and at the zenith at midnight in October-November.

The bright grouping of stars has been observed and named by most ancient cultures of the world. These include the Celts, Maori, Aboriginal Australians, the Persians, the Arabs, the Chinese, the Japanese, the Maya, the Aztec and the American Indians, the Sioux and the Cherokee. In Hinduism, the Pleiades are known as Krittika, a reference to six sisters who raised Kartikeya, the son of Shiva. There are also references to the Pleiades in records from Babylonia, over 20 centuries BCE and even in a 3,600 year old bronze disk of the Unetice culture, discovered in Germany.

The Pleiades cluster is also of interest in formal astronomy and astrophysics, as being a cluster, and not merely stars along nearly the same line of sight. It had been worked out in 1767 that the probability of a chance alignment of so many bright stars was only 1 in 500,000, which strongly suggests that the Pleiades must be physically related. This has since been confirmed, by comparison of the apparent motion of the stars with reference to the Solar System, that they were moving together.

The group of stars are now known to be a relatively young formation of hot blue and very luminous stars in the early stages of development. The Pleiades are also among the nearest cluster to the earth, which makes them so clearly visible to the naked eye. This feature has also made it possible to estimate their distance from the earth. As there is a relationship between the real brightness of star and its colour, which indicates its temperature, knowing the distance of the Pleiades helps estimate the distances of other stars of which we know only the colour and the reduced brightness as apparent here on the earth.

Date of Sappho's poem

The aim of the study by the Texas and Thailand trio, the authors say in their paper, was to take a fresh look at the seasonal dating of Sappho‘s Midnight Poem. Earlier estimates were based on considerations like, “ it is in early spring that poets’ thought turn towards love”, or the study by Herschberg and Mebius in 1990, largely based on descriptive arguments. The effect of precession of the equinoxes, or the cyclic change in the orientation of axis of the earth reference to the plane of its orbit around the sun, was also taken into account by Herschberg and Mebius, but they did not employ modern astronomical software to accurately estimate the local time of the sighting.

The present study is based on working out the exact date on which the Pleiades formation would have set, taking the year 570 BCE as reference. The researchers used the software package, Starrynight, which produces sky maps of any year of choice, like the sky over Bethlehem on the first Christmas or of asteroid near-hits predicted even centuries from now. And along with this they also used the night sky snapshots for 570 BC using the Digistar 5 software, which works out the night sky for projection on the dome of the planetarium.

The result of the work was that the earliest date the Pleiades could have set at midnight in 570 BCE is 25th January. On earlier dates, the Pleiades would have set after midnight. As we are not sure of the timekeeping device that Sappho may have used to know when it was midnight, the researchers also checked out till what date the Pleiades would have been visible at all, after dusk, at night. This date was found to be 6th April.

The conclusion is hence only that time the poem refers to is between midwinter and early spring, a result which is in keeping with earlier estimates, including that of Herschberg and Mebius. That the astronomical record by Sappho in the course of a poetic sally should be confirmed as scientifically accurate is to build a bridge between ancient literary and scientific creativity. “Sappho should be considered an informal contributor to early Greek astronomy as well as to Greek society at large,” Manfred Cuntz says. Not many ancient poets comment on astronomical observations as clearly as she does.”

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