Great Comet of 1744

Discovery

The comet was discovered on November 29, 1743, by Jan de Munck at Middelburg,{{cite book and was independently sighted on December 9, 1743 by Klinkenberg at Haarlem, and by Chéseaux from the observatory at Lausanne on December 13. Chéseaux said it lacked a tail and resembled a nebulous star of the third magnitude; he measured the coma as five minutes across.

The comet brightened steadily as it approached perihelion. By February 18, 1744, it reportedly was as bright as the planet Venus (with an apparent magnitude of −4.6) and at this time displayed a double tail.

Perihelion, "six tails"

The comet reached perihelion about March 1, 1744, when it was 0.2 astronomical units from the Sun. At about this time it was bright enough to be observed in daylight with the naked eye. As it moved away from perihelion, a spectacular tail developed — extending well above the horizon while the comet's head remained invisible due to the morning twilight. In early March 1744, Chéseaux and several other observers reported an extremely unusual phenomenon — a 'fan' of six separate tails rose above the horizon.

The tail structure was a puzzle to astronomers for many years. Although other comets had displayed multiple tails on occasion, the 1744 comet was unique in having six. It has been suggested that the 'fan' of tails was generated by as many as three active sources on the cometary nucleus, exposed in turn to solar radiation as the nucleus rotated. As each area is exposed to sunlight it becomes active and ejects material. The rotation period calculated by this method is hours.

It also has been proposed that the tail phenomenon was a very prominent example of the "dust striae" seen in the tails of some comets, such as Comet West and C/2006 P1 (McNaught).

Other observations

Chéseaux, on March 9, was the last known observer in the Northern Hemisphere to see the comet, but it remained visible for observers in the Southern Hemisphere, some of whom reported a tail length of approximately 90 degrees on March 18. The comet was not seen after 22 April 1744.

In Tunkhungia Buranji(A medieval Ahom text), The comet finds mention as being seen for three successive Assamese months, Push, Magh and Phagun from 1665–1666 Saka (equivalent to 1743–1744 in the Gregorian calendar)

The comet also was noted in Japanese astronomical records in the Nihon Odai Ichiran of the Kanpō era. | trans-title= Annales des empereurs du Japon Researchers have found in Chinese astronomical records that some Chinese observations describe audible sounds associated with the comet, which may, if true, have resulted from the interaction of particles with the Earth's magnetosphere, as sometimes described for the aurora.{{cite web | access-date= 2008-11-17 | archive-date= 2015-09-24 | archive-url= https://web.archive.org/web/20150924040007/http://www.ips.gov.au/Educational/1/1/2 | url-status= dead }}

Among those who saw the comet was the thirteen-year-old Charles Messier, on whom it had a profound and inspirational effect. He went on to become one of the founding figures of modern astronomy, and later discovered many comets during his observations.

Catherine the Great, then Sophia, also observed the brilliant comet as a young girl as she was travelling to Russia to be wed.

Orbit

The comet has a perihelion distance of 0.22 AU. The data collected during 1744 were used to calculate parabolic orbits. However, Olof Hiorter suggested that the Great Comet of 1402 was a previous apparition based on the appearance of the comet and roughly similar orbits, and that the comets of 1058 and 715 were also previous apparitions of the comet. Heinrich Wilhelm Matthias Olbers and Johann Holetschek agreed with this claim. Maik Meyer and Gary Kronk calculated an orbit based on the observations of the 1744 apparition without limitations in the values that indicates an eccentricity of 0.995580 and an orbital period of 354 years, while a parabolic orbit has larger residuals. Excluding the daylight observations the orbital period is calculated to be about 480 years, indicating the comet has an orbital period of a few hundred years. Based on the unrestricited orbit and including planet perturbations, Meyer and Kronk found a perihelion at about 1405.

Meyer and Kronk integrated the orbit backwards for an apparition in 1402 and compared the results with the chronicle reports of the Great Comet of 1402, finding that the reports about the location and the appearance of the comet were in agreement with an estimated perihelion on 25 March. They also searched for older apparitions and based on the backwards calculated orbits the found candidate comets in 1032, 676, 336 AD, 44 BC for previous apparitions. The comet of 1032 is described in a Chinese source indicating a perihelion in early August, when the geometry is such that observations are difficult. Based on that the previous apparition was the comet of 676, a bright comet observed in autumn mentioned in many European and Asian sources. The backwards integrated orbit of the 1744 comet indicates a perihelion at 4 November 676 and a previous apparition in 336, when a comet was observed, and in mid 44 BC. In 44 BC a bright comet was visible, known as Caesar's Comet, however the observation reports are contradicting and do not fit well the predicted appearance.

Based on these associations, Meyer and Kronk predict the comet could return in 2097, with an estimated perihelion date assumed to be around 8 December 2097, but there are significant uncertainties.{{cite journal | doi-access= free }}

Notes

References

| doi-access= free | arxiv= 1204.2285

| access-date= 17 November 2008 | archive-date= 7 April 2023 | archive-url= https://web.archive.org/web/20230407204015/https://www2.jpl.nasa.gov/comet/news66.html | url-status= dead }}

References

1. Bhuyan S. K.. (1933). "Tungkhungia Buranji Or A History Of Assam 1681–1826a.d.".
2. Robert K. Massie. (2012). "Catherine the Great: Portrait of a Woman". Random House Trade Paperbacks.