Wayward Comet:. Martin Beech

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СКАЧАТЬ href="#ulink_e55e3204-891e-529e-a1e2-c48feac02b8e">table 1.3 for details.

label	Comet	Designation	P(yr)	e	i (°)	notes
A	1748	C/1748 H1	---	1.00	94.54
B	1742	C/1742 C1	---	1.00	112.95
C	1744	C/1743 X1	---	1.00	47.14	(1)
D	1533	C/1533 X1	---	1.00	149.59
E	1748	C/1748 K1	---	1.00	67.08
F	1706	C/1706 F1	---	1.00	55.27
G	1678	6P/d’Arrest	6.62	0.67	2.81	(2)
H	1707	C/1707 W1	---	1.00	88.65
I	1743	C/1743 C1	---	1.00	2.28
K	1702	C/1702 H1	---	1.00	3.38
L	1699	C/1699 D1	---	1.00	109.42
M	1739	C/1739 K1	---	1.00	124.26	(3)
N	1743	C/1743 Q1	---	1.00	134.42
O	1718	C/1718 B1	---	1.00	148.84

Table 1.3. Details of the comets studied by Nicolaas Struyck. Column 1 is the letter labeled as used in his illustration (our figure 1.21). Column 2 is the year of the comet as given by Struyck, while column 3 provides the present-day cometary identification. Columns 4, 5 and 6 indicate the orbital period (technically infinite if the orbit is parabolic: e = 1.00), the eccentricity and orbital inclination. Notes: (1) Often identified as Chéseaux’s comet, this comet ranks as one of the greatest in all of history. It was remarkable for being both very bright and for showing multiple tails. (2) The linkage between comet C/1678 R1 and periodic comet 6P/d’Arrest was made by Carusi et al., in 1991. In his 1753 study Struyck deduced a parabolic orbit. Heinrich Louis d’Arrest discovered his comet in June of 1951, indicating a remarkable 41 returns to perihelion since the 1678 sighting. (3) This is the parent comet to the October Leonis Minorid meteor shower.

      With Struyck we see the first 3-dimensional, albeit on a 2-dimensional page, rendition of cometary orbits. And accordingly the Solar system takes-on a more dynamical feel: the sedate and circular motions of the planets being enveloped in a Gordian knot of cometary paths. The image also hints at the distinct possibility that collisions might occasionally occur between planets and comets – this being more apparent, in some strange optical sense, than in the case of the standard 2-dimensional diagrams (e.g., figure 1.19), where the orbits must, of necessity, cut across each other. It is as if by adding the third dimension, the real threat of cometary collisions is lifted, literally, right from the page – it is the real solar system that is now being portrayed, raw and primordial. No longer the neatly drawn and ordered orbital diagram of the earlier philosophers, the 3-dimensional cometarium of Struyck reveals the inner solar system to be dynamic and perhaps, alarmingly, somewhat overcrowded. Isaac Newton had already hinted at the possibility of collisions between comets and planets in his Opticks (1704), and William Whiston (recall figure 1.19) had additionally suggested that a comet passing close by the Earth might have precipitated the biblical deluge. Furthermore, Whiston argued that comets, “seem fit to cause vast mutations in the planets, particularly in bringing on them Deluge and Conflagration…. [they are] instruments of Devine vengeance upon the wicked inhabitants of any of these worlds” (here Whiston is invoking the commonly held idea at that time that all of the planets in the solar system were inhabited). Indeed, Newton writes, “whence is it that Nature doth nothing in vain; and whence arises all that Order and Beauty which we see in the World? To what end are comets, and whence is it that Planets move all one and the same way in orbs concentrick, while Comets move all manner of ways in Orbs very eccentrick”. The general idea that comets might on occasion collide with a planet, and specifically Earth, however, was not a strongly supported idea during either the 18th or 19th centuries. Indeed, a form of group denial, in effect, set-in during these centuries, with philosophers choosing to believe that the solar system was so well ordered and so well constructed that collisions were either impossible, negligibly rare, or, if they occurred at all, were for very specific God-ordained purposes. And indeed, as a mirror to the heavens, so it was on Earth too – the idea of slow, gradual change, rather than catastrophic punctuations, was dominant amongst natural philosophers and the proof of concept was provided for by Charles Lyell in his highly influential, multi-volume, Principles of Geology (published between 1830 and 1833).

      Not all predictions concerning comets come true, and such was the situation with the (non)comet of 1789. Highlighted as one of Edmund Halley’s originals, it had been reasoned that the comets sighted in 1532 and 1661 were one and the same, and with an apparent period of some 129 years its return some time circa 1789 was expected. Indeed, Bartholomew Burges in his work, A short account of the solar system and comets in general: together with a particular account of the comet that will appear in 1789 (published in 1789), reasoned that, “we may reasonably expect the comet in question, to be visible towards the latter end of 1788 or the beginning of the year 1789, and certainly some time before the 27th of April 1789”. For all of the great confidence that Burges invested in his prediction, no comet appeared. In spite of pinning his hopes upon the wrong cometary return, Burges’s text remains interesting because of two attached СКАЧАТЬ