Part Two: Early Moderns: Nicholas Copernicus (1473-1543), Johannes Kepler (1571-1630), and Sir Isaac Newton (1642-1727)

by sprincipe2012

          Part Two:

    

Early Moderns: Nicholas Copernicus (1473-1543),  

                   Johannes Kepler (1571-1630), and Sir Isaac Newton (1642-1727)

Professor Alexander Jones’ lectures (University of Toronto, Winter 2002) on ancient Babylonian and Greco-Roman astronomy, for me, highlighted by the Greeks’ conception of the Great Celestial Wheel of the sun, moon, planets and stars, all revolving round the arth at the centre. He concluded those lectures with a brief account of what happened fourteen hundred years after Claudius Ptolemy completed his masterful exposition, Almagest, the accomplishments of Greco-Roman astronomers up to his time in the 2nd century CE..

In the early modern period, Copernicus advanced the idea that the sun lies at the centre is but one of the planets going around the sun (an unorthodox idea first proposed by the ancient Greek astronomer, Aristarchus of Samos, 310-230 BCE). In 1510, Copernicus circulated a small paper he called Little Commentary (not published until the 19th century) “All the orbs encompass the sun which is, so to speak, in the middle of them all, for the centre of the world is the Sun” Our “terrestrial orb,” Earth, revolves round the sun like any planet. He went on to say that the arth accomplishes a rotation around its fixed poles, while the heavens remain motionless (not quite true).

Copernicus spent the rest of his life labouring at six books entitled Revolutions of the Heavenly Spheres, only published at his death. Evans that Copernicus thought he had discovered “the true system of the world,” a system that unified all the parts in that the six known planets: Mercury, Venus, Earth, Mars, Jupiter and Saturn encircle the sun in this orderly concentric pattern (not unlike Eudoxus in Plato’s time who conceived of the “nested spheres” of sun and planets). According to Evans, because Copernicus assumed that Earth moves around the Sun at uniform speed on a circle eccentric to the Sun, was essentially Ptolemy’s modelcircular motion around an off-centre point in the circle.

Kepler began his university studies in Italy in philosophy and theology, but on being introduced to Copernicus’ theory, he moved to astronomy. Evans illustrates a diagram that inspired Kepler Mysterium cosmographicum ( in Latin, ‘The Mystery of the Universe’998:428) show(like the ancient Greek mathematician, Archimedes) that angles could be inscribed within a circle. He used each angle as the point of an equilateral triangle to represent the successive conjunctions of Jupiter and Saturn as they rotate on their respective orbits inside this larger circle. Much later, Kepler would determine Earth’s own orbit by triangulations, adapting this similar geometric device from Ptolemy, but by this time, Kepler was inscribing unequally-shaped triangles that  elliptically-shaped pattern.

Kepler’s major work was published in 1609 entitled Astronomia nova (New Astronomy). His life-time achievements were monumentally important thereafter. Evans notes that part of the significance of work was that he moved astronomy away from mathematics into the realm of physics (likely an inspiration to Newton), by relying on observational data for his breakthrough interpretations of planetary orbits like Mars’.

As found in “New Astronomy,” Kepler speculated regarding a physical solution for understanding planetary behaviours – the answer might lie in “Magnetic motive forces” (Evans 1998:440), an idea which Newton was to develop much further.

                         Newton explaining Solar System by Physics

      The genius of Newton is recognized for his explanation as to why the planetary bodies continually rotate around the sun. His theory rested upon the insight that the more powerful gravitational force of the sun (today set at 27 times the gravity of Earth at 1) keeps pulling the planets around itself. The planets are satellites of the sun, just as moons notably Jupitertwelve(Jupiter’s gravity field is twice that of Earth’s). Newton saw that there are inter-planetary gravitational influences, most significantly Jupiter, of course, along with its large planetary companion, Saturn. When these two are in conjunction, closer together, their combined force-field impacts to some degree on the force-field of the sun itself, provoking solar eruptions and flares of such exceedingly great physical energy that these solar particles of energy stream down into our atmosphere in greater abundance.

Kepler’s discovery of the elliptical shape of planets led to Newton’s gravitational theory, explaining why Mars’ orbit is rather elongated; it is affected by proximity to Jupiter, as is Mercury’s orbit more elongated because it  the sun. Earth’s orbit is only slightly elliptical; at times, it tends towards near ut its gravitational  smaller-sized Venus deforms that planet’s orbit to some degree.

           In order to appreciate Newton’s Laws of Universal Gravitation, e.g. F= G and M divided by R, which took some twenty years for him to develop, we shall select some important considerations that occurred to NewtonBernard Cohen discusses ‘Newton on the Laws of Motion’; William Harper examines ‘Newton’s argument for universal gravitation;’ and Curtis Wilson  discusses the definitions offered by Newton in his Principia, including what Newton meant by “gravity”

Cohen says that Newton’s understanding of terrestrial gravity is that it is the force that causes bodies to descend downward “… toward the centre of the Earth.” This became part of hislaws of universal gravitation. Then, he said of gravity, there is “… the force by which the planets are continually drawn back from rectilinear motions and compelled to revolve in curved lines.” Cohen quotes Newton from the Principia, that, starting from the law of inertia, a body moves uniformly straight forward unless compelled to change its state by forces impressed.

Wikipedia explains the above idea more simplistically. If the sun with its powerful force-field, 27 times the gravity of Earth, were not holding Earth in a quasi-circular orbit, Earth might just keep heading off into space in a straight line. In Newton’s time, his contemporary Halley calculated the orbital path of the comet named after him. The elongated orbit of Halley’s comet, originating like other comets and asteroids from the area in space between Jupiter and Mars, while en route to the sun, must deviate in this path whenever it by-passes an intervening planet like Earth.                 

Harper  Newton’s consideration of the orbits of the four moons (then known) of Jupiter. From other’s observations, understood the orbits of those moons approximate uniform motion on concentric circles. Jupiter is the centre that directs their orbits. Harper says that Newton saw the sun as centre of planetary motions, and their departure from uniform “ a little more swiftly in their perihelia and more slowly in their aphelia” Regarding inter-planetary relationships, Newton said that:

“We have proved that all planets are heavy [or gravitate] toward one

another and also that the gravity toward any one planet, taken by

itself, is inversely as the square of the distance of places from the

centre of the planet (2002:190)

Wilson (2002:202) looks at some observations  Jupiter and Saturn. In the 1690’s, Newton was asked to help correct Kepler’s values; it seemed that Jupiter was moving faster Saturn. What Newton proposed was complex. From his acquaintance with Kepler’s elliptical model, he advised that he would take the focus of Saturn’s orbit by the centre of gravity in Jupiter and the Sun. Then, he would introduce oscillations into Saturn’s eccentricity of orbit.  Newtondid not offer the mathematical calculations for the preceding suggestions.

In 1787, Laplace dealt with such anomalies in eccentricity by giving an explanation for the acceleration in the motion of Earth’s moon. He said that, “if there was a decrease in Earth’s eccentricity, this would lead to a diminution of the Sun’s perturbing force – and thus, the moon’s motion would accelerate”2002:216).

Earth’s orbit is only slightly elliptical at present, at 0.015 degrees its closest approach to the sun in early January some five million kilometers

By our calendar, the effect of the above is that the  four seasons  not exactly equal. James Evans sets the dates as follows: the spring equinox is March 21; on June 22, it reaches its northerly limit at summer solstice Autumn equinox occurs on September 23; and the winter solstice on December 22 – explained according to Earth’s slightly elliptical orbit at present.

Today’s astronomers, A. Berger and M.F. Loutre, calculate that Earth’s orbitmoving towards near-circularity in 10,000 years’ timEarth’s orbit is due to become almost a perfect circle. Eccentricity will no longer be a major factor in altering Earth’s speed of motion at different times of the yearow will its uniform and constant motion affect the Moonrotational phases? Or, for that matter, how will it affect the specific dates in our calendar that currently separate the four seasons?

                   Accounting for the Great Ice Age: Earth’s Elliptical Orbit

        In 1837, the Swiss scientist, Louis Agassiz, an authority on fossil fish, made a presentation to the Swiss Society of Natural Sciences which soon to become known as his theory of the “Great Ice Age.” Agassiz had been struck by seeing boulders, later called “erratics” strewn about in the Swiss Alps which he proposed must have been deposited by glaciers as they retreated. With new eyes, he and his colleagues looked at layers of till composed of dirt and stones which must have lain at the edges of the vast ice fields that once covered most of Europe.

During the 1860’s, a Scottish scientist, James Croll, proposed a theory of glacial-interglacial phases which he linked directly to changes in Earth’s elliptical orbit. According to Croll, whenever Earth was farthest away from the sun, at aphelion in the season of winter, then there would be colder winters and glacial conditions. On the other hand, if Earth was passing  to the sun when perihelion was in the season of summer, this brought about interglacial conditions. Furthermore, he that slight changes in the tilt of the earth’s axis could influence the creation of an ice age. Whenever the tilt was closer to upright, this would reduce the amount of sunlight reaching high latitudes. , whenever the tilt was pointing downwards to a more pronounced degree, more ice would melt in the northern regions and an interglacial would be initiated.

Croll proposed that the last Ice Age began some 250,000 years ago and then ended 80,000 years ago, at which time he thought the present interglacial had its inception. This chronological aspect of Croll’s theory was discounted after scientists found that the present interglacial began some 15,000 years ago. , Croll’s idea of combining two astronomical factors, the eccentricity of Earth’s orbit and axial tilt, was the prelude to Milutin Milankovitch’s more ambitious attempt to track past climate epochs according to the interactions of the three different cycles: orbital eccentricity, the degree of obliquity of Earth’s axis, and the precession of the seasons of perihelion/aphelion.

                            Gribbin’s and Gribbin’s Ice Age, 2001

          John and Mary Gribbin’s treatment of past ice ages in Ice Age (2001) focuses on the importance of the astronomical cycles formulated by Milutin Milankovitch (dates 1879-1958). Early in the 20th century, Milankovitch, a Serbian mathematician and astronomer, undertook the mammoth task of computing, with pencil and paper, the “mean irradiance” of sunlight received in the higher latitudes, 55-60-65 degrees North over the past 650,000 years. According to the Gribbins (2001:45), drew from calculations made by a contemporary,  Ludwig Pilgrim (1904), who computed variations in orbital eccentricity, precession and tilt over the past million years

Milankovitch published papers in 1912, 1913 and 1914 in his own Serbian language without attracting any attention from astronomers or geologists. In 1924, the Russian-born Wladimir Koppen and the German geologist, Alfred Wegener (the latter became known for his theory of continental drift), collaborated on Climates of Geological Prehistory wherein they referred to Milankovitch’s theory of glacial-interglacial epochs.

In contrast to Croll’s theory, as above, Koppen, a climatologist, suggested that an interglacial takes place whenever snow from the preceding winter season melts away in the summertime precluding the build-up of ice sheets from year to year. The latter argument for the importance of ice accumulations surviving through summer seasons came to be accepted by Ice Age theorists.

                         Substantiating Milankovitch’s Climate Cycles

        The Gribbins the efforts by earth scientists during the mid-20th century who searched for the physical evidences of Milankovitch’s cycles, chronologies that could fit the astronomical indications of past glacial and interglacial epochs. In the chapter, ‘Deep Proof” (2001:62-90), the detail successive attempts to read a dating-framework sea-core material of ooze drilled up from ocean depths, paying close attention to the shells of little sea creatures called “forams.” Eventually, scientists realized that changes in global temperatures could be read according to two different kinds of oxygen isotopes. During the interglacials, oxygen 16 prevail in fresher waters in the oceans, and during a glaciated period, oxygen 18 show greater salinity in the colder ocean waters. During warmer periods, the lighter oxygen 16 evaporates from the surface waters, turning into the snowfall that steadily built up in northern regions, then stored in the ice as an ice age progresses. With oxygen 16 locked up in the ice and with global temperatures lower, the heavier element of oxygen 18 predominate in ocean waters to form the shell bodies of little sea creatures.

Beyond these ocean core studies, other earth scientists looked at raised beaches high above present-day beaches. These raised beaches existed when sea levels were much higher during interglacials. As well, in various landscapes, scientists found great layers of loose soils, loess, deposited during the preceding ice age when atmospheric conditions were very cold and dry, and the winds blew the dry soils across the barren landscapes.

According to the Gribbins (2001:75), raised beaches have been found in Atlantic and Pacific regions indicating that during the last interglacial termed the “Eemian,” c 120,000 years ago, the sea level was six meters higher than today. Various methods of dating show that sea levels were highest at 125,000 years ago, 105,000 years ago, and 82,000 years agoperiods roughly correspond to Milankovitch’s warming epochs.

                     Updating Astronomical Imprints on the Past Ice Age

                                       and the Last Interglacial

           Belgian astronomer and paleo-climatologist M.F. Loutre (2003), looks back at previous astronomical calculations of climate changes by orbital factors, still of historical interest in having influenced, for instance, Croll’s chronologies as above. More importantly, he presents his colleague, Berger’s more accurate refinement of these astronomical factors in keeping with the basic Milankovitch model.

First, let us briefly look at Loutre’s examples of past efforts in this regard – Figures 2 and 4 present two graphs outlining astronomical calculations of major changes over the past 600,000 years for high latitudes 60-75 degrees N (the main focus of Milankovitch’s calculations)the first graph, ‘A,’ represents Stockwell and Pelgrem (the latter, presumably Pelgrem’s calculations from 1904 which Milankovitch utilized)second graph, ‘B,’ replicates Leverrier (19th century) and Miskovitch’s  “astronomical solution.”  graphs correspond to each other in indicating similar timing of peaks and troughs; the latter indicating cooler epochs are shown as shaded notches pointing downwards – most marked at 230,000 and 200,000 BP. A smaller depth of trough is shown at 115,000 and at 75,000 BP. At 25,000 BP, there is a very little notch (though it is now known that the climate was moving towards the Last Glacial Maximum which ended c 18,000 BP). Likely Croll’s mistaken supposition that the last Ice Age began some 250,000 years ago and ended at 80,000 BP was based upon the comparative depths of notches for cooler conditions at 250,000 and 200,000 BP.

Looking at Part C, Berger’s calculations for mean irradiance the past 600,000 years, I select the time frame from 130,000 BP to the present. extremely high amounts of sunlight/heat at 130,000 BP during the last interglacial epoch known as “the Eemian.” Then he line descends sharply to lows at 115,000 BP Loutre  higher vegetation levels (which presumably were associated with the luxuriant growth of the Eemian) could have prevented the inception of another ice age at 115,000 BP. his is an important consideration for today’s concern regarding  CO 2 concentrations. During present interglacial, carbon concentrations have now reached 390 ppmv, versus the levels of 270 ppmv during the Eemian.

Berger’s graph line rises again at 100,000 BP, after which up and down lines show that at 80.000 BP there was still ample sunlight at higher latitudesAt 70.000 BP, the Last Ice Age must have gotten underway. The obliquity of the axis was closer to upright at 22.5 degrees off vertical, reducing amount of sunlight reaching polar regions. Although eccentricity remained fairly high at 0.0degrees, perihelion was in winter and aphelion in summer, the latter effect tending to  new ice levels from completely melting away during summer months.

a global crisis. Sometime around 75,000-70,000 BP, a super-volcano explosion took place in the Far East, on Toba, causing a world-wide winter. As vegetation died, there was famine, and many early human groups died out. Likely that volcanic event was a primary factor in triggering the onset of the Great Ice Age which, for the most part, endured until the very deep freeze of the Last Glacial Maximum, c 20,000 BP. We may also note that, at 50,000 BP, the obliquity of earth’s tilted axis was at its smallest angle from the vertical, at 22.1 degrees, further reducing the receipt of sunlight at the high latitudes

Some 40,000 years ago, paleo-climatologists speak of a period of fluctuating temperatures, the saw-toothed episodes of weather changes. Environmental Change: The Evolving Ecosphere, speaks of  “stadial-interstadial climatic shifts known as Dansgaard-Oeschger cycles of short-lived climatic deteriorations” throughout the last glacial epochthat, “rbital forcing is unlikely to drive these swift climatic changes”We can suppose, however, that the short-lived weather fluctuations often generated wetter and more moisturous conditions producing abundant snowfalls, converted over time into ice fields.

Returning to Loutre’s article, Figure 4 (2003:999), taken from Berger, separates out the orbital features of eccentricity, climatic precession (opposite seasons of perihelion and aphelion), and obliquity of Earth’s axial tilt. What can we read here of the highlights of the Last Interglacial, the Eemian, at 125,000 BP? At 130,000 -125,000 BP, eccentricity was high at 0.04 degrees (compared to present eccentricity at 0.015 degrees). Warmer summers would have been the case with perihelion in summer, and aphelion in winter. The obliquity of earth’s axial was pronounced c 24.5 degrees, exposing higher latitudes to maximum amounts of sunlight (compare to today’s obliquity at medium range of tilt, 23.5 degrees).  Even though at 115,000 BP, obliquity reached an extremely reduced tilt at c 22 degrees, eccentricity of orbit remained high which would have helped to sustain higher temperatures.

Loutre’s Figure 7 (2003: 1003) shows estimated ice volumes connected to ocean core data regarding the oxygen isotope records. It shows the most increase in ice volumes at 140,000 BP (prior to onset of the Eemian) and then at 20,000 BP – the Last Glacial Maximum. Loutre concludes: “This model confirms that the orbital forcing acts as a pacemaker for theglacial-interglacial cycles and that climate response to orbital forcing isamplified by CO 2.” Elsewhere, Loutre comments upon the extended epoch of warmth during the Eemian epoch

” At the last interglacial, some 125 ky BP, modeling experiments led to

warmer conditions, especially in the high latitudes, reduced sea-ice,

enhanced northern tropical monsoon, and northward displacement of

the tundra and taiga…However, the strong cooling induced by changes

in the orbital parameters at 115 ky BP are not sufficient to initiate

glaciation, at least if vegetation changes are not taken into account.”

Anatomically Modern Humans South Africa during                                              

            Several years ago, during classes at the University of Toronto on

paleo-anthropology, we students learned of the exciting new reports from archaeological sites in South Africa. The findings at Blombos Cave and Klasies River point to the last interglacial, the Eemian, as a period that favoured exceptional advances for anatomically modern human beings, our inventively-minded, Homo Sapiens ancestors. Towards the end of the last Interglacial, c 110,000 BP, in cave sites at Klasies River, Eastern Cape, South Africa, archaeologists found specimens of teeth and jawbone fragments belonging to a modern human. They carefully measured the dimensions and wear on different molars and one incisor, finding that some appear smaller, more “gracile” or delicate-looking as the term implies. Other specimens are larger and more “rugged,” but still within modern ranges for size. Rightmire and Deacon ‘New human teeth from Middle Stone Age deposits at Klasies River, South Africa,’ deduce that this population exhibits what they call “sex dimorphism The size difference are between male and female remains of people who towards end of Last Interglacial.

Blombos Cave situated along the southern coastline of South Africa, dated 100,000 to 70,000 years ago, (lowest date-levelso far at 130,000 BP) found only seven human teeth (not described). But, here, the cultural remains tell the story of those early modern humans making new adaptations in this ideal beach-setting next to the Indian Ocean. At that time, the sea level was much higher and the cave opened onto the shores of the ocean where they foraged for marine foods like mussels and turtles, and adapted shells for vessels.

Since 1991, Blombos Cave archaeologists, led Christopher Henshilwood, have undertaken careful excavations, finding much use of coloured ochre for decorating stone and bone tools, perhaps body paint, as well perforated sea shells for ornamentation – altogether considered cognitive advances. Their diet was diversesea creatures like turtles, land mammals of different kinds, ostrich eggs and fish bones. They had begun to fashion nicely cut bifacial blades as spear points, leaf-shaped.

That interglacial epoch saw the beginning of the climate changed and deteriorated, they explored farther afield following continental coastlines. Some reached as far as the Middle East and south eastern Asia, ultimately reaching Australia some 60,000 years ago (thus escaping increasingly severe glacial conditions further to the north).

                Future Long Term Climate Projections: Berger and Loutre

      The mentioned A. Berger and M.F. Loutre of the Belgian Institute of Astronomy and Geophysics published an article entitled ‘An Exceptionally Lengthy Interglacial Ahead?’ in Science’s Compass, June 2008 ().  the common assumption held thirty years ago that interglacial interludes last about 10,000 years assumption was based on the approximate duration of last two interglacials.  understanding of the interglacial phases of the past Quaternary is now called into question.

Some 400,000 years ago, at the inception of the full cycle of variations in Earth’s orbit, there was a lengthy interglacial known as “marine isotope 11” which produced warm temperatures due to the particular astronomical forcings of that era. Berger’s diagram, Figure 4, showed that over the next 100,000 years from the present arth’s eccentricity of orbit will hardly rise beyond today’s very slight eccentricity. astronomers assert that, over the next 25,000 years, arth’s orbit will be moving towards almost perfect circularity at 0.00. such low eccentricity perihelion and aphelion times of the year will not bring Earth as close to or as far from the sun as took place in the past. The impact of such minimized eccentricity of orbit on Earth’s seasons will produce less extremes of cold and heat.

Naturally, Berger and Loutre discuss the ongoing issue of CO 2 concentrations, of such concern today, noting, as mentioned, that the current CO2 at 370 ppmv is higher than the 290 ppmv during the Eemian. They suggest these global warming trends due to human causes will need to be factored into any projections for future global temperatures.

                       Short-Term Variability in Weather Conditions

          Unusually, March 17th, 2015 brought a dazzling display of Aurora Borealis (Northern Lights) to this Toronto region, mid-latitude 43 degrees, even as Aurora Australis lit up the night skies over Australia and New Zealand, 40th parallel. One would not expect to see in one’s lifetime such a spectacle of green, red, orange and blue dancing in wavy patterns over the northern part of the night sky.

These few years of unexpectedly glacial winter conditions, marked by the Aurora Borealis appearing in Toronto environs, cannot be easily explained by Milankovitch factors. Another explanation is needed for shorter term weather conditions.

        Journal of Atmospheric and Solar-Terrestrial Physics‘A shared frequency set between the historical mid-latitude aurora records and the global surface temperatures’critiques the current anthropogenic (i.e. human-caused) global warming theorinclined to dismiss astronomical forcings of the climate system, such as the Milankovitch model proposed. He comments upon uncertain theorizing regarding “the aerosol forcings and climate sensitivity to GHG changes,” as well as, “their inadequate modeling of the cloud system, ocean dynamics and the biosphere”

In this paper focusing on mid-latitude aurora events, Zafetta synthesizes aurora frequencies with periodicities of sun, moon and the major planets, Jupiter and Saturn. He proposes a series of shorter-term temperature conditions in Earth’s climate, which fluctuate between warmer and cooler phases, and which periodicities closely correspond to the other cycles within our solar system”

Zafetta mid-latitude aurora events (such as happened in Toronto at 43 degrees latitude on March 17th, 2015) records kept since the 1700’s. He explains these events the excessive electrification of Earth’s electro-magnetic field due to incoming cosmic radiations and charged particles in the solar wind whenever they enter Earth’s electro-magnetic field with greater than usual penetration.

This is not a completely novel theory. Roy Gallant (Earth’s Changing Climate, 1979:33-35) discusses flares emanating as storms on the sun, extending over enormous distances from the sun, which predominate over an elevenyear cycle – the Jupiter effect and gravitational fields. He refers to a Manhattan observatory  1946 that “magnetic storms” could interfere with radio communications.

Zafetta explains that if Earth’shappens to be weak,  bombardment by electrically charged particles reaching Earth from solar eruptions or the solar wind. Normally, aurora displays are a remarkable feature in high-latitude polar regions butfails to keep the cosmic radiations at bay, they stream down into the mid-latitudes

As mentioned, Zafetta finds that mid-latitude aurora events (he also takes into account high-latitude aurora patterns) have a periodicity that is similar to other cycles in the solar system, most importantly whenever the Sun is reacting to presence of Jupiter and Saturn. Thus he suggests “a possible planetary origin of the aurora, and temperature oscillations” in Earth’s climate system. He refers to others who have related the physics of such relationshito the effect that”…. solar variation can be partially driven by the planets throughgravitational spin-orbit coupling mechanisms and gravitational  tides”

Jupiter’s orbital cycleequates closely with the Sun’s sun-spot cycle, c 11years. Jupiter with a gravity of 2 compared to Earth’s1 (the Sun at 27 times Earth’s gravity) generates the strongest gravitational tides when its orbit takes it most closely to the sun, but especially when conjunct with Saturn on the same side of the sun.

Zafetta (2011:151) combines Jupiter and Saturn as follows: Jupiter’s siderial period is 11.862 (similar to the sun), while Saturn’s is 29,457 periodicity; thus, their combined orbits when repeated or doubled approximates 59.6 to 61 years. There is the sunspot cycle, doubled, at c 22 years. he significant periods to bear in mind are: 10-11, 20-22, and 50-63 years. He relates certain solar-lunar cycles, e.g., the Saros lunar eclipse cycle of 18.03 years, to periodicities of mid-latitude aurora events.

Richard Huggett (1997: 40-43) covers these , beginning with the sunspot cycle, averaging 11.14 years; the whole “heliomagnetic cycle” is doubled at 22 years and involves the reversal of the sun’s magnetic field, which, he says, “influences cycles of terrestrial magnetic activity and the atmospheric production of isotopes.” In his section on planetary cycles, Huggett says: “… the jostling of the planets and the sun leads to variations in the Earth’s orbit.”

Zafetta suggestmid-latitude aurora eventcharacterized by frequencies a Soli/Lunar tidal cycle of 9.1 year period, the motion of the sun relative to the barycentre of the solar system, and overall periods of 10-10.5, 20-21, 30 and 60-62 ranges of years. proceeds to relate cloud system on earth to such astronomical cyclesassert “there exists anharmonic modulation of the electric properties of the earth’satmosphere that modulates the clouds and, therefore, theterrestrial albedo” He proposes that the level of atmospheric ionization and the global electric circuit must be involved somehow in regulating the cloud system. He further that cloud acts as an albedo mechanism in itself, helping to cool the Earth.

In keeping with the above 60 year full cosmic cycle, which Zafetta divides into 30 years of cooling and 30 years of warming,dentifies the following weather phases: a warming period from 1850-1880, a cooling from 1880-1910, a warming from 1910-1940, a cooling from 1940-1970, and a warming from 1970-2000. He speaks of a small cooling since 2000, which may last until 2030-2040.

                     Polar Vortex shifts impacting on mid-latitude weather

            Zafetta’ssuggestion of a cooling phase from 2000-2030-2040 would have seemed nonsensical during the last several years of record high average global temperature – until now. We have experienced unusually deep cold during the past two winters in northeastern mid-latitudes, North America.

so-called  “Cold-Snaps” of late have evoked discussions of the increased waviness of the northern Jet Stream, now dipping further to the south at times. Meteorologists regard this phenomenon as a response in some way to rapid Arctic warming. Jennifer Francis of Rutgers’ University observes that “very wavy jet stream patterns have been occurring since the 1990’s,” accounting for the recent weather extremes in North America.