Prehistoric Astronomy and the Younger Dryas Catastrophe?

[Michael B-C]

Without this 23° tilt the ecliptical plane would be simply coplanar with Earth's equatorial plane so tilt doesn't create ecliptic. It means that zodiac would simply consist partly or completely of different constellations. And due to different visible size of constellations, I can imagine, that in the "pre-tilt" zodiac some (probably the smaller ones) constellations would be "replaced" by others while others (the bigger ones) would "remain" and that zodiac itself would possibly even consist of a bigger or smaller number of constellations.

Hi Altair. Yes indeed, thank you; excuse my rather cack-handed description of the effects of the tilt re ecliptic and zodiac. But I think it does still mean that in particular the northern hemisphere sky from the equator up would have had a markedly different look to today, with as you say the zodiac consisting partly or completely of different constellations. That was my main line of thought regarding its implications when extrapolating the zodiac of today back to the symbols at Gobekli Tepe.

[Altair]

Hi Altair. Yes indeed, thank you; excuse my rather cack-handed description of the effects of the tilt re ecliptic and zodiac. But I think it does still mean that in particular the northern hemisphere sky from the equator up would have had a markedly different look to today, with as you say the zodiac consisting partly or completely of different constellations. That was my main line of thought regarding its implications when extrapolating the zodiac of today back to the symbols at Gobekli Tepe.

Yes, it would be different. Would be interesting to find out to what extent it would differ.

Added: without this tilt there would be no seasons and no equinoxes and possibly no reason for the people on Earth to create zodiac.

[mrtn]

没有太阳还是旅行沿着倾斜h the same stars in the sky as seen from earth, because it is the axis of earths rotation that is tilted, not the orbit of the earth. Alignment from earth to sun to the stars behind doesn't change. Over the year the position of the sun and stars in the sky wouldn't wobble in a wave fashion. The sun at noon would (seen from one place on earth) be the same height from the horizon in December and June or any other month. On the north pole it would be shadow permanently and you would see the same stars the whole year (the latter is the case now as well, just with a different pole star).A bit further south on earth the sun would travel constantlyonthe horizon, never rising or setting other than caused by land features. But still the stars behind the sun would be the same as they are now in a particular season. What a year is would be measurable只有by the sun-stars relation, when the stars (moving parallel to the horizon) behind the sun have traveled 360° and the sun is in the same sign again. But note that sun and stars travel parallel to the horizon only over the course of the year, but seen from a certain point on earth they would still rise and set during over the course of a day.

As for thecanceledtext above, I think that was wrong. If you go south and come out of the pole shadow then the sun would just rise very slightly for a moment in the day, but would also travel deeper below the horizon at night, when your position on earth is on the nightside facing outer space away from the sun.

Does that make sense?

[Altair]

Anotherpiece of evidencefor Younger Dryas Impact Hypothesis. The paper attached.

The Younger Dryas interval at Wonderkrater (South Africa) in the context of a platinum anomaly
J.F. Thackeray, L. Scott & P. Pieterse

Received 1 March 2019. Accepted 23 August 2019

Abstract

Wonderkrater in the Limpopo Province in South Africa is a late Quaternary archaeological site with peat deposits extending back more than 30 000 years before the present. Palaeoclimatic indices based on multivariate analysis of pollen spectra reflect a decline in tempera- ture identifiable with the Younger Dryas (YD).A prominent spike in platinum is documented in a Wonderkrater sample (5614) with a mean date of 12 744 cal yr BP using a Bayesian model, preceding the onset of the YD cooling event. The YD platinum spike at Wonderkrater is the first to be observed in Africa in the southern hemisphere, supplementing new discoveries from Patagonia in South America, in addition to more than 25 sites with such platinum anomalies in the northern hemisphere.The observations from South Africa serve to strengthen ongoing assessments of the controversial YD Impact Hypothesis, whereby it is proposed that a meteorite or cometary impact contributed to a decline in temperature, associated inter alia with dispersion of atmospheric dust, mammalian extinctions and cultural changes.

[...]


Figure 1. Map showing the location of Wonderkrater in South Africa, in relation to more than 25 other Younger Dryas (YD) sites which also have anomalies in platinum concentrations (orange dots) in deposits dated at circa 12 800 cal yr BP. Red dots represent sites with other YD impact proxies including spherules, as well as nanodiamonds as reported for example by Kurbatov et al. (2010). The Pilauco site in Patagonia (southern Chile) and Wonderkrater are as yet the only known sites in the southern hemisphere where YD platinum spikes have been reported. Map drawn after Pino et al. (2019). North and Central America map source: USGS, Sioux Falls; Japan ASTER Program (2003), ASTER Global Digital Elevation Map, GDEM-10 km-BW, fromASTER Global Digital Elevation Map, 10.5067/ASTER/ASTGTM.002.

DISCUSSION AND CONCLUSIONS

The platinum spike in sample 5614 at Wonderkrater precedes the onset of the Younger Dryas cooling event (Fig. 2a,b). Since strong evidence for spikes in platinum has been obtained for the YD interval from more than 25 sites in Europe, Asia and North America (e.g. Kennett et al. 2009, 2015; Petaev 2013; Moore et al. 2017) as well as Mexico (Israde-Alcantara 2012) and Patagonia (Pino et al. 2019),
and now also at Wonderkrater in the southern hemi- sphere (Fig. 1), the Younger Dryas Impact Hypothesis is in part supported, recognizing criticisms expressed by Pinter et al. (2011), Holliday et al. (2014) and others. One criticism (Tankersley et al. 2018) is that火山活动可以铂(apa的来源rt from cosmic impacts), but no volcanic activity has been documented in southern Africa within the late Quaternary.

The YD Impact Hypothesis expresses the view that Terminal Pleistocene extinctions can be attributed to a cosmic impact. Without invoking any one particular causal factor, we note the occurrence of terminal Pleisto- cene extinctions of fauna such as Equus capensis, Syncerus antiquus, Megalotragus priscus and Antidorcas bondi in South Africa (Klein 1972 1978; Faith 2011, 2012, 2013a,b, 2014; Thackeray 1980). However, a YD impact cannot account as an instantaneous causal factor since Megalo- tragus (for example) persists in the interior of the country at Wonderwerk (probably at low population densities) until about 7500 BP (Thackeray 2015).
Megafaunal extinctions in South Africa may be attrib- uted to both environmental change and human predation within a period of time before and after 12 800 cal yr BP.

然而,在数据的基础上提出了圣udy, it may be cautiously considered that the consequences of a hypothesized YD cosmic impact (and the dispersion of atmospheric dust) may have contributed to some extent to the process of extinctions not only in southern Africa, but also to that which occurred in North and South America as well as Europe, recognizing synchroneity of Pt anomalies (Kennett et al. 2015) that has been cited in support the Younger Dryas Impact Hypothesis.

We note that in terms of culture, the apparently abrupt change from Robberg to Oakhurst technocomplexes in South Africa as documented, for example, at Boomplaas Cave in the southern Cape (H.J. Deacon 1979 1995; J. Deacon 1982 1984), penecontemporary with the Younger Dryas, is closely co-incident with the cultural change from Clovis to Folsom technologies in North America.The question as to whether this relates indirectly if not directly to a common causal YD cosmic impact is beyond the scope of this article which serves primarily to report a YD plati- num anomaly in the Wonderkrater sequence.

Apart from Wonderkrater, the Younger Dryas cooling interval has been detected from the analysis of pollen in hyrax middens (Chase et al. 2011, 2013, 2015, 2018) and also from oxygen isotope records from terrestrial Achatina snails at Bushman Rock Shelter (Abell & Plug 2000) and marine mollusc shells from Elands Bay (Cohen et al. 1992).Notably, the cultural change between Robberg and the Oakhurst techno-complexes at the former site occurs at about the time of the YD (Mitchell 1988; Lombard et al. 2012 ; Porraz et al. 2015).

The suggestion that the hypothesized YD impact is related in particular to the Hiawatha crater in northern Greenland remains to be conclusively determined on the basis of absolute dates. However, it can already be noted that the large crater rim (31 km in diameter) has not been subject to substantial erosion, and glacial ice older than 12 800 BP is missing (Kjær et al. 2018). Irrespective of where an impact might have occurred, the YD Impact Hypothe- sis is supported in part by this study of the Wonderkrater Core 3 sequence in South Africa in which a platinum spike is reported for sample #5614, with a mean date of 12 744 cal yr BP using Scott’s (2016) Bayesian model, preceding the onset of the YD cooling event.

This is the first evidence in Africa to partially support the YD Impact Hypothesis on the basis of a platinum anomaly in a late Quaternary sedimentary sequence. The Pilauco site in Patagonia in southern Chile (Pino et al. 2019) and Wonderkrater are as yet the only known sites in the southern hemisphere where YD platinum spikes have been reported, supplementing the corresponding evidence from more than 25 sites in the northern hemisphere, dated circa 12 800 cal yr BP.

[Carl]

New research supports hypothesis that asteroid contributed to mass extinction

A team of scientists from South Africa has discovered evidence partially supporting a hypothesis that Earth was struck by a meteorite or asteroid 12 800 years ago, leading to global consequences including climate change, and contributing to the extinction of many species of large animals at the...

phys.org

A team of scientists from South Africa has discovered evidence partially supporting a hypothesis that Earth was struck by a meteorite or asteroid 12 800 years ago, leading to global consequences including climate change, and contributing to the extinction of many species of large animals at the time of an episode called the Younger Dryas.

教授领导的团队,弗朗西斯·萨克雷of the Evolutionary Studies Institute at the University of the Witwatersrand in Johannesburg, South Africa, discovered evidence of a remarkable "platinum spike" at a site called Wonderkrater in the Limpopo Province, north of Pretoria in South Africa.

.............

A large crater 31 kilometers in diameter has been discovered in northern Greenland beneath the Hiawatha Glacier. "There is some evidence to support the view that it might possibly have been the very place where a large meteorite struck the planet earth 12 800 years ago," says Thackeray. "If this was indeed the case, there must have been global consequences."

Thackeray's team believes their discovery of a platinum spike at about 12 800 years ago at Wonderkrater is just part of the strengthening view that an asteroid or cometary impact might have occurred at that time.

This is the first evidence in Africa for a platinum spike preceding climate change. Younger Dryas spikes in platinum have also been found in Greenland, Eurasia, North America, Mexico and recently also at Pilauco in Chile. Wonderkrater is the 30th site in the world for such evidence.

"Our evidence is entirely consistent with the Younger Dryas Impact Hypothesis" says Thackeray.

一个大的小行星撞击地球的概率in the future may seem to be low, but there are thousands of large rocks distributed primarily between Jupiter and Mars. One in particular, classified as Apophis 99942, is referred to as a "Potentially Hazardous Asteroid." It is 340 meters wide and will come exceptionally close to the Earth in 10 years' time.

"The closest encounter will take place precisely on Friday April 13, 2029," says Thackeray. "The probability of the Apophis 99942 asteroid hitting us then is only one in 100 000, but the probability of an impact may be even higher at some time in the future, as it comes close to Earth every 10 years."

Are people actually waking up to this? I can't help but postulate that the increasing widespread appeal of the YD Impact Hypothesis in this timeline is due in large part to Laura's efforts many years ago.

Also I'm starting to see an uncanny number of little "data points" pointing at the date range of 2025-2030 as the place where things could get really really "interesting".

[Vulcan59]

The American Geophysical Union nowsupports Younger Dryas event.

Abstract
新仙女木(码)突然冷却事件(9 ~ 12日00 yr to 11,600 yr) represents a brief return to severe cold conditions in mid- to high- latitudes in the Northern Hemisphere. The cooling is thought to have resulted from freshwater flooding of the northeast Atlantic and/or the Arctic Oceans that prevented deep water formation and promoted extensive southward expansion of sea-ice. Two different triggers that would lead to freshwater capping the north Atlantic have been proposed: (1) catastrophic drainage of proglacial Lake Agassiz and (2) a meteorite impact-related partial destabilization and/or melting of the Laurentide ice sheet. However, the physical evidence for these triggers remains elusive. Recent revision in the age of Laacher See volcano (Volcanic Explosivity Index = 6) in Eifel, Germany has led to the suggestion that the YD event was triggered by emplacement in the stratosphere of large amounts volcanic sulfur and halogens with sustained cooling resulting from a positive feedback involving sea ice expansion and/or AMOC shutdown. Thus, building of sea-ice rather than freshwater capping provides a trigger according to this hypothesis. Here, we use GRIP ice core to investigate whether the YD was engendered by a one-time catastrophic event or whether it was an integral part of a sequence of events that unfolded as the last ice-age came to a close. We sampled GRIP ice core every 9 cm from a depth of 1659.35 m to 1664.30 m corresponding to a time-resolution of 2-3 years spanning 12,939-12,810 yr b2k. Decontaminated ice-core was analyzed for δ18O, δD, major cations and anions, trace-elements, and osmium and lead isotopes. We find that a massive volcanic eruption occurred at 12,918 yr b2k and that immediately following the eruption the d-excess increases from 4 to 9 permil over a period of 37 years indicating a profound increase in sea-ice. During this time period, ratio of fluxes mantle to continental derived osmium also increases. Additionally, there is evidence of a 20-fold increase in extra-terrestrial osmium flux ~12,819 yr b2k following which the δ18O values display a steep and sustained decline to –40 permil.These signals suggest that volcanism potentially induced the YD cooling, which may have been further exacerbated by an extra-terrestrial impact.

[Pierre]

The American Geophysical Union nowsupports Younger Dryas event.
[...]
These signals suggest that volcanism potentially induced the YD cooling, which may have been further exacerbated by an extra-terrestrial impact.

That's the least mainstream science could concede knowing the overwhelming evidence of cometary impacts ca. 12,800 BP.

However their statement is still misleading. I don't think that volcanism induced cooling was worsened by an extraterrestrial impact but rather that multiple extraterrestrial impacts induced the YD cooling and triggered volcanic eruptions too.

The thing is, recent history of our planet is marked by numerous ice core dust spikes that are systematically attributed to volcanic eruptions.
Problem is, for most spikes there's no eruption with matching date!

The diagram above shows SO2 (sufur dioxide) concentrations in GISP2 (Greenland) ice core over the past 16,000 years :

It shows 62 spikes that reach more than 120 ppm. Some of the spikes reach 800 ppm. For comparison, the "giant" Krakatoa eruption generated about 150 ppm of sulfur.

Out of those 62 major spikes, only 14 aretentatively火山爆发有关。最大的两个ones (-10,657 BC and -9,285 BC) have no associated eruption whatsoever.

It raises an obvious question: "how many ice core dust spikes are wrongly attributed to volcanic eruptions while being the result of cometary events (direct impact or overhead explosion)?"

[thorbiorn]

It shows 62 spikes that reach more than 120 ppm. Some of the spikes reach 800 ppm. For comparison, the "giant" Krakatoa eruption generated about 150 ppm of sulfur.

Out of those 62 major spikes, only 14 aretentatively火山爆发有关。最大的两个ones (-10,657 BC and -9,285 BC) have no associated eruption whatsoever.

To go from 150ppm for Krakatoa to 800 ppm sounds like a lot, but Krakatoa is really far away from Greenland being just south of the equator. Would it have made a difference if it had been closer? At least the distribution is not always uniform. Below are two pictures showing the situation near an erupting volcano and near a smelter, but the question is at what altitude the concentrations were found, and if some of the sulfur would be removed by precipitation in the form of snow, rain or hail?

https://www.researchgate.net/publication/253011406_Enhanced_monitoring_of_sulfur_dioxide_sources_with_hyperspectral_UV_sensors

More on sulfur emissions from volcanoes and earth quakes
OnStratospheric sulfur aerosols - Wikipediathere is:

Sulfur aerosols are common in thetroposphereas a result ofpollutionwithsulfur dioxidefrom burningcoal, and from natural processes.Volcanos are a major source of particles in the stratosphere as the force of thevolcanic eruptionpropels sulfur-containing gases into the stratosphere.The relative influence of volcanoes on the Junge layervaries considerably according to the number and size of eruptions in any given time period, and also of quantities of sulfur compounds released. Onlystratovolcanoescontaining primarilyfelsicmagmas[Felsic refers tosilicate minerals,magma, androckswhich are enriched in the lighter elements such assilicon,oxygen,aluminium,sodium, andpotassium.]are responsible for these fluxes,asmaficmagma [Mafic is an adjective describing asilicate mineralorigneous rockthat is rich inmagnesiumandiron, and is thus aportmanteauof magnesium andferric.[1]] erupted inshield volcanoesdoesn't result in plumes which reach the stratosphere.

Creating stratospheric sulfur aerosols deliberately is a proposedgeoengineeringtechnique which offers a possible solution to some of the problems caused byglobal warming. However, this will not be without side effects[2]and it has been suggested that the cure may be worse than the disease.[3]

Stratospheric sulfur aerosols - WikipediaWhat is useful about this information is that volcanic origin would involve a stratovolcano, and rather than one big stratovolcano what if a few smaller ones went off at the same time? From the distinction between felsic and mafic lava one might be led to the idea that not all volcanoes release equally much sulfur. There was an article from2018's biggest volcanic eruption of sulfur dioxidewhich mentioned that:

2018's biggest volcanic eruption of sulfur dioxide
Date:February 28, 2019Source:NASA/Goddard Space Flight CenterSummary: The Manaro Voui volcano on the island of Ambae in the nation of Vanuatu in the South Pacific Ocean made the 2018 record books. A NASA-NOAA satellite confirmed Manaro Voui had the largest eruption of sulfur dioxide that year.

The Manaro Voui volcano on the island of Ambae in the nation of Vanuatu in the South Pacific Ocean made the 2018 record books. A NASA-NOAA satellite confirmed Manaro Voui had the largest eruption of sulfur dioxide that year.

The volcano injected 400,000 tons of sulfur dioxide into the upper troposphere and stratosphere during its most active phase in July, and a total of 600,000 tons in 2018. That's three times the amount released from all combined worldwide eruptions in 2017.

During a series of eruptions at Ambae in 2018, volcanic ash also blackened the sky, buried crops and destroyed homes, and acid rain turned the rainwater, the island's main source of drinking water, cloudy and "metallic, like sour lemon juice," said New Zealand volcanologist Brad Scott. Over the course of the year, the island's entire population of 11,000 was forced to evacuate.

At the Ambae volcano's peak eruption in July, measurements showed the results of a powerful burst of energy that pushed gas and ash to the upper part of the troposphere and into the stratosphere, at an altitude of 10.5 miles. Sulfur dioxide is short-lived in the atmosphere, but once it penetrates into the stratosphere, where it combines with water vapor to convert to sulfuric acid aerosols, it can last much longer -- for weeks, months or even years, depending on the altitude and latitude of injection, said Simon Carn, professor of volcanology at Michigan Tech.

In extreme cases, like the 1991 eruption of Mount Pinatubo in the Philippines, these tiny aerosol particles can scatter so much sunlight that they cool the Earth's surface below.

The map above shows stratospheric sulfur dioxide concentrations on July 28, 2018, as detected by OMPS on the Suomi-NPP satellite. Ambae (also known as Aoba) was near the peak of its sulfur emissions at the time. For perspective, emissions from

Hawaii's Kilauea and the Sierra Negra volcano in the Galapagos are shown on the same day. The plot below shows the July-August spike in emissions from Ambae.

"With the Kilauea and Galapagos eruptions, you had continuous emissions of sulfur dioxide over time, but the Ambae eruption was more explosive," said Simon Carn, professor of volcanology at Michigan Tech. "You can see a giant pulse in late July, and then it disperses."

The OMPS nadir mapper instruments on the Suomi-NPP and NOAA-20 satellites contain hyperspectral ultraviolet sensors, which map volcanic clouds and measure sulfur dioxide emissions by observing reflected sunlight. Sulfur dioxide (SO2) and other gases like ozone each have their own spectral absorption signature, their unique fingerprint. OMPS measures these signatures, which are then converted, using complicated algorithms, into the number of SO2 gas molecules in an atmospheric column.

"Once we know the SO2 amount, we put it on a map and monitor where that cloud moves," said Nickolay Krotkov, a research scientist at NASA Goddard's Atmospheric Chemistry and Dynamics Laboratory.
These maps, which are produced within three hours of the satellite's overpass, are used at volcanic ash advisory centers to predict the movement of volcanic clouds and reroute aircraft, when needed.

Mount Pinatubo's violent eruption injected about 15 million tons of sulfur dioxide into the stratosphere. The resulting sulfuric acid aerosols remained in the stratosphere for about two years, and cooled the Earth's surface by a range of 1 to 2 degrees Fahrenheit.

This Ambae eruption was too small to cause any such cooling. "We think to have a measurable climate impact, the eruption needs to produce at least 5 to 10 million tons of SO2," Carn said.

Still, scientists are trying to understand the collective impact of volcanoes like Ambae and others on the climate. Stratospheric aerosols and other volcanic gases emitted by volcanoes like Ambae can alter the delicate balance of the chemical composition of the stratosphere. And while none of the smaller eruptions have had measurable climate effects on their own, they may collectively impact the climate by sustaining the stratospheric aerosol layer.

"Without these eruptions, the stratospheric layer would be much, much smaller," Krotkov said.

Earthquakes can also lead to the outgassing of sulfur:Outgassing of hydrogen sulfide and other gases off Kaikoura Peninsula, New Zealand -- Sott.net

Sulfur coming from the impact of meteorites
The above idea of more sulfur being present in felsic magma led to the idea that stony meteorites may contain more sulfur than iron meteorites, but the Wikis had little to say about sulfur in stony meteorites:Chondrite - Wikipediaor iron meteorites:Iron meteorite - Wikipedia
There was one paper claiming the content of sulfur in chondrites is much much higher than in the other elements they tested selenium and tellurium, but those being rare this is not a surprise:https://www.researchgate.net/public...abundances_in_chondrites_and_their_components

More interesting is the following:

When an asteroid or comet impacts a planetary body, it releases a tremendous amount of energy.Except for objects smaller than a few meters, the impacting asteroid or comet is obliterated by the energy of the impact.The impactor material is mixed with the target material (the rock on the planet's surface) and dispersed in the form of vapor, melt, and rock fragments.

During the impact, sulfur in the impactor or in sulfur-containing target rocks can be injected into the atmosphere in a vapor-rich impact plume. In some impact events, such asChicxulub, the rocks hit by the impactor contain sulfur.Sedimentary rocks hit by an impactor sometimes include large amounts of evaporites. Evaporites are rocks that are formed with minerals that precipitated from evaporating water, such as halite (rock salt) and calcite (calcium carbonate). Two other very common evaporite minerals are gypsum (CaSO4 + H20) and anhydrite (CaSO4), both of which contain sulfur (S).

Projectiles also contain sulfur-bearing minerals, particularly the mineral troilite (FeS), which is obliterated in an impact event. This material releases its sulfur, which is then injected into the stratosphere. The amount of sulfur injected into the stratosphere depends partly on the composition of the projectile, which can vary from one crater to another.Using chemical traces of the projectiles left at impact craters, scientists can determine the type of meteoritic material involved. Using this data, scientists can then calculate the amount of sulfur each specific impact injects into the stratosphere.The amount of this sulfur can be substantial, because meteoritic materials contain up to 6.25 weight percent sulfur.Consequently, even if the asteroid or comet does not hit a S-rich target, it can still cause dramatic increases in the total amount of atmospheric sulfur.

Once vaporized, this sulfur can react with water to form sulfate (or sulfuric acid) particles. These particles can greatly reduce the amount of sunlight that penetrates to the surface of the earth for a period of up to several years.Over time, the sulfate will settle out of the stratosphere (upper atmosphere) into the troposphere (lower atmosphere) where they can form acid rain which can have additional environmental and biological effects.

There was probably an impact on Greenland about 10,000 BC but might that have led to a spike in the content of sulfur?Hiawatha Glacier - Wikipedia

To sum up the above possible ideas of where to look for an explanation for the spikes of sulfur found in the Greenlandic ice cores they could be related to one or more stratovolcanoes or earthquakes leading to a release of sulfur, but some volcanoes release much more sulfur than others. A spike in sulfur could be a result of a large impact releasing sulfur contained in the material of the impactor and or released from the impacted rock.

[Pierre]

To sum up the above possible ideas of where to look for an explanation for the spikes of sulfur found in the Greenlandic ice cores they could be related to one or more stratovolcanoes or earthquakes leading to a release of sulfur, but some volcanoes release much more sulfur than others. A spike in sulfur could be a result of a large impact releasing sulfur contained in the material of the impactor and or released from the impacted rock.

A lot can be said about the confusion between volcanic eruptions vs. cometary events regarding dust spikes found in ice cores (and more generally catastrophes). I address this topic in an article that was published today: "Volcanoes, Earthquakes And The 3,600 Year Comet Cycle"

[thorbiorn]

A lot can be said about the confusion between volcanic eruptions vs. cometary events regarding dust spikes found in ice cores (and more generally catastrophes). I address this topic in an article that was published today: "Volcanoes, Earthquakes And The 3,600 Year Comet Cycle"

Thank you for the latest article linking the Younger Dryas event to a few other comet events.
The article mentions the Hiawatha crater in Greenland, I tried to look up some more information about this impact and found from 2018 a paper with the title:A large impact crater beneath Hiawatha Glacier in northwest Greenland
[ Also as pdf onhttps://advances.sciencemag.org/content/advances/4/11/eaar8173.full.pdf]
The article mentions the geology of the place, but to get a better understanding I looked up other sources. The article also explains what the impact event could have looked like, by far the most interesting part. Still, I will begin with the geology, because if there was ejecta from this impact then they ought to reflect some of the local compositions of the rocks around the crater.

The geology in the area of Greenland where the Hiawatha crater is located.
A large impact crater beneath Hiawatha Glacier in northwest Greenlandmentions:

ice-marginal飘忽不定的构成巨石derived from beneath Hiawatha Glacier indicates that the identified structure was formed within the same types of highly metamorphosed Paleoproterozoic terrain as mapped across most of Inglefield Land, which is part of the east-west–trending Inglefield mobile belt (fig. S1)

More details of the geology of the Inglefield Land can be found on page 12-23 in this document:https://eng.geus.dk/media/12967/map1_p01-48.pdfWhile there is marble in the area, it is more common a little away from the Hiawatha area, where the crater was found. In the Hiawatha area there appears to be more granite like rocks, at least on the surface. While I looked into this, I wondered what would happen if marble got heated by an impact. Marble is CaCO3 and it it was heated to 840 degrees Celcius, it would release the CO2 and become CaO.CaOhas a molar mass af about 57 g/mole whileCaCO3has a molar mass of just above 100 g/mole. This would mean that for every ton of superheated marble one would have 430 kg of CO2.
There is more on the geology in this abstract, and there one learns there may be sulfur rich deposits in the region:https://www.researchgate.net/public...orthwest_Greenland_A_new_mineralisation_stylehas:

Inglefield Land in northwest Greenland is an ice-free 7000 km² region underlain by the Palaeoproterozoic Inglefield mobile belt,composed ofquartzo-feldspathic gneisses, meta-igneous and supracrustal rocks. These rocks are unconformably overlain by an unmetamorphosed cover of sedimentary and igneous rocks of the Mesoproterozoic Thule Basin and the Lower Palaeozoic Franklinian Basin. Mineralisation in Inglefield Land is characterised by a copper–gold metal association that can be classified in terms of the hosting rocks, namely: garnet–sillimanite paragneiss-hosted, orthogneiss-hosted and mafic–ultramafic-hosted. The paragneiss-hosted mineralisation, the topic of this paper, is essentially confined within a NE-trending structural corridor and consists of bands of sulphide±graphite-bearing, hydrothermally altered, quartzo-feldspathic gneiss, called “rust zones”. These are commonly parallel to the paragneiss main foliation, suggesting a close relationship. The rust zones have strike lengths from a few metres to more than 5 km, and widths ranging from a few centimetres to 200 m.Sulphides mainly include pyrrhotite, pyrite and chalcopyrite. The sulphides form disseminations, up to 30% by volume, but in places they form massive pods or lenses up to 20–30 m, and about 0.1–0.5 m wide.Graphite contents are up to 5 vol.%.Rust zones typically consist of a quartz–plagioclase mosaic associated with a late generation of red-brown biotite, sericite, chlorite and epidote. Mylonitic or cataclastic textures are locally recognisable. XRD analyses of graphite indicate temperatures of between 650 and 700 °C. Sulphur isotope analyses show δ³⁴S values ranging from −6.2‰ to +9.3‰

And one last sources about the geology of the area is:Alba Mineral Resources Plc (AIM:ALBA) Further exploration ground secured at Inglefieldwhich mentions:

· GEUS has identified that Inglefield Land has the potential for copper-zincvolcanogenic massive sulphide (VMS) deposits, which are associated with and created by volcanic-associated hydrothermal events in submarine environments

· Previous extensive surface sampling has reported anomalous copper (up to 1.39%), gold (up to 1.7g/t), cobalt (up to 0.16%), vanadium and nickel

· High grade float reported to have been collected in West Inglefield historically, returning 8.8% cobalt and 7.6% nickel, showing the significant potential of the region

Next to the more interesting part about the creation of the crater InA large impact crater beneath Hiawatha Glacier in northwest Greenlandthey mention that they did not find any ejecta that they could yet correlate with what ought to be there if it had come from the Hiawatha area.

Preliminary estimates of impactor and ejecta properties.The diameter of an impact crater constrains the kinetic energy of the impactor.The formation of a 31-km-wide impact crater in crystalline target rock requires ~3 × 10^21 J of energy(17). Assuming that the Hiawatha impactor was iron with a density of 8000 kg m−3 and its impact velocity was 20 km s−1, the required impactor diameter was ~1.5 km (17).The impact would initially produce a bowl-shaped cavity ~20 km in diameter and ~7 km deep, which would quickly collapse (within~1min) to form a complex crater more than 31 km in diameter and ~800m deep with a central uplift(17). This impact scenario would have melted and vaporized up to ~20 km3 of target rock, approximately half of which would have remained within the crater, forming a melt sheet up to ~50 m deep.

No ejecta layer that might be associated with the Hiawatha impact crater has yet been identified in either Greenland’s rock or ice records. If no ice was present at the time of a high-angle (>45°) impact, then the
symmetric ejecta layer would be ~200 m thick at the rim, thinning to less than 20m at a radial distance of 30 km from the rim (17). However, during most of the Pleistocene, an ice sheet covered the impact area
(18). If ice was present and its thickness was comparable to the impactor’s diameter, then a more energetic projectile is required to produce a crater of the observed size, and the fraction of non-ice debris in the ejecta would be smaller than if the impact hit ice-free land (19). Furthermore, regionally extensive ice cover at the time of impact could have resulted in a significant fraction of the ejecta landing on the ice-sheet surface of the Greenland or Innuitian ice sheets, rather than on bare ground. As the crater is situated very close to the present ice margin, the site has almost certainly been ice free during one or several short
(~15 ka) interglacial periods during the Pleistocene, such as predicted for the Eemian ~125 ka ago (20).On the basis of present ice-flow speeds (Fig. 1B), most impact ejecta deposited onto the ice sheet would have
been transported to the ice margin within ~10 ka. Similarly, based on Holocene vertical strain rates (21), any such ejecta would be less than half of its original thickness within 10 ka.

如果格陵兰冰盖出席of impact and a high-angle impact occurred during the late Pleistocene (LGP), then ejecta ought to be present in the four deep ice cores from central and northern Greenland that span the majority of the LGP (fig. S5), but none has yet been identified.At two of the ice cores (GISP2 and GRIP) located farthest (>1000 km) from the crater (fig. S5), the expected initial thickness of a symmetric ejecta layer for a Hiawatha-sized impact on rock is ~0.7 mm with an average particle diameter of ~0.4 mm (17). In the closer ice cores (fig. S5), this thickness increases roughly twofold.If ice were present at the impact site, then a significant fraction of the ejecta would also be ice (19), but the presence of any rock ejecta should be unambiguous in an ice core.A possible complicating factor to interpreting the absence of ejecta in ice cores south of the structure is thepresently unknown angle of impact.Modeling indicates that oblique impacts (<45°) produce asymmetric ejecta predominantly downrange of the crater with an ejecta-free shadow zone up range and that this effect becomes more pronounced as the impact angle decreases (22).The Hiawatha impact crater is located farther north (78.72°N) than any other known impact crater, a position that increases the probability of a northward-directed oblique impact given the majority of Earth-crossing asteroids that move in or near the ecliptic plane.Such a scenario might be analogous to the late-Jurassic Mjølnir crater,which is also large (40 km diameter), is high latitude (73.8°N), andproduced an asymmetric (northward focused) ejecta layer (23).

Because it is not yet known whether the Greenland Ice Sheet covered this region at the time of the impact, or its thickness at that time or the impact angle, our estimates of impactor size, initial crater size, impact melt volume, and ejecta thickness and extent should be considered preliminary.

Age of the Hiawatha impact crater
[...]
Radar evidence of active basal melting(full-column radiostratigraphic synclines) and subglacial water storage (groundwater table) within andbeneath Hiawatha Glacier,respectively, appear to be anomalousas compared to grounded ice-marginal settings across northern Greenland. Possible basal melting could be due to an anomalous subglacial heat source and isconsistent with, but not conclusive of, residual heat from the impact itself.Previous modeling of hydrothermal systems within martian subaerial impact craters suggests that such systems have a life span of ~100 ka for a 30-km-wide crater (31). For the terrestrial Hiawatha impact crater, the overlying ice sheet would have provided an ample supply of water for such a hydrothermal system during the Pleistocene and Holocene,but it would have also exported heat more efficiently from that system than for a subaerial crater, which suggests a shorter life span of any possible post-impact hydrothermal system than on Mars.

Apparently the

It may be that the impactor making the Hiawatha crater did not leave as many traces in the icecore, as one might expect due to the angle of impact and other factors,.All that is still to be settled, but reading this paper was a minor shock for me. Imagine a ball of iron with a diameter of 1.5 km moving at more than 70,000 km per hour making a 20 km wide and 7 km deep hole in the earth within fractions of a second which then all collapses within about a minute leaving a 31 km crater that is only 800 meters deep. but still the residual heat from the impact would be expected to linger on for thousands of years - in one of the coldest places on the planet. That is scary, don't you think?

On this page there are some illustrations of the crater:SVS: The Hiawatha Impact Craterlike:

A still image showing a comparison of the size of the Hiawatha crater to Washington, DC.

A still image showing a comparison of the size between the Hiawatha crater and Paris, France. The region shown is limited by the Paris super-périphérique (A86) ring road around the city.

This image shows another view of some radar data from the airborne survey of the Hiawatha crater displayed on opaque curtains. A blue bar indicates the height of one kilometer. The blue arrow points to one of the central peaks.

[Pierre]

Imagine a ball of iron with a diameter of 1.5 km moving at more than 70,000 km per hour making a 20 km wide and 7 km deep hole in the earth within fractions of a second which then all collapses within about a minute leaving a 31 km crater that is only 800 meters deep. but still the residual heat from the impact would be expected to linger on for thousands of years - in one of the coldest places on the planet. That is scary, don't you think?

Quite scary indeed. It makes the whole "global warming" hysteria all the more derisory where activists freak out about an hypothetical 0.2°C warming over the next 10 years.

The Hiawata crater also shows how little is known and how little is invested to discover, understand and properly date impact craters. How many unfound craters are on Earth's surface? How many craters have been barely investigated? How many craters don't have a proper dating?

The same could be said for ice cores, for which crucial markers like platinum, iridium, mercury, nanodiamonds... are rarely investigated (apart for the 12800 BP event that is now recognized as a cometary impact).

I think if impact craters and ice cores were thoroughly investigated, it would clearly appear that cometary events (impacts and/or overhead explosion and/or electric interactions) are way more frequent and destructive than currently believed.

Actually, after perusing this topic for a while, I've come to the idea that cometary events might well be the greatest modulator of life on Earth in general, and the rise and fall of civilizations in particular.

[Gandalf]

Posts that didn't belong to this thread have been movedhere

[thorbiorn]

Actually, after perusing this topic for a while, I've come to the idea that cometary events might well be the greatest modulator of life on Earth in general, and the rise and fall of civilizations in particular.

似乎是so, although comets would not be able to explain, I think, a Cambrian explosion of the many different species "evolving" as if they had come custom made. Such an event may connect with the influence of other densities, although rarely observed there are glitches in our reality. The title of the book you wrote was Earth Changes and the Human-cosmic Connections and it is very meaningful, but I am wondering if one could consider the order of the words differently and read them as The Human-cosmic Connection and Earth Changes, or should we rather say The Cosmic-human connection and Earth Changes.

Below there are a couple of excerpts that helped me to think about the topic of cyclical comet cludters, and after that I will return one more time to a few calculations, as I was trying to find patterns in the flux of comets; not that I succeeded, but I tried.

Session 22 January 2000

01-22-2000 Ark, Laura, Frank Q: Hello. A: Hello. Q: And who do we have with us this evening? A: Anoova. Q: And where do you transmit through? A: Cassiopaea. Q: As you know, the morning after the last session, I woke up in extreme pain. It took several weeks to get this under...

www.silwale.com

(L) Now, there is a lot of talk about the imminent stockmarket crash, so I put up the financial info on the site without any specific advice. Could you comment on this potential for a major crash or depression happening this year?

A: Is there not always an "imminent" crash/depression?

Q: Of course there is! It's like the Weekly World News predicting the imminent End of the World about once a month. Eventually, they will be right! (A) Maybe not. (L) Well, another thing that was brought up in our discussion with this new gal in the mail group was that nothing of any importance of significance would happen in terms of transition on the earth for at least another thousand years or so. She was saying that we would slowly transform for the next thousand years, and there would be no cataclysms or earth changes. I am wondering if this is a new option that has come up because of changes in consciousness?

A: It may be. But remember,the "future" is merely a matter of which reality one experiences in real time, so called. It is merely which of those that exist shall the menu selectors elect?

And before that:

Session 23 March 1996

March 23rd, 1996 Laura, Frank, V [The very beginning of the second side of the tape has a noise anomaly as follows; it starts out sounding like the taped voices are soft, far away and coming from the bottom of a well. This clears up; the voices are clearer and nearer. Then, they sound far...

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A: Now, for the remainder of this session,we wish to address the so called earth changes for your benefit,as you are stuck here. Those present need to be equi... [Sound anomaly on tape begins here, on second side.] ...pped to stop buying into popular deceptions once and for all! Reread Bramley.

Q: (L) Funny I took him off the shelf today... (V) What's Bramley about? (L) Well, hold on. Do you want me to read it right now?

A: No.

Q: (L) Ok, address the subject.

A: All such changes are caused by three things and three things only! 1) Human endeavors. 2) Cosmic objects falling upon or too near earth. 3) Planetary orbital aberrations.

Q: (L) All right, carry on.

A: Don't believe any of the nonsense you hear from other sources. It is designed to facilitate mass programming and deception.

Q: (L) Ok, okay.

A: Just as your bible says; "You will know not the day, nor the hour." This means there is no warning. None. No clue. No prophecy. And these events... [anomaly starts again here, briefly.] are of the "past" as well. [and ends here.]

Q: (V) What events of the past, as well?

A: Cosmic and "man made" cataclysms.

Q: (L) Well, since you put 'man-made' at the top of the list, am I to infer that perhaps some of the activities of the consortium, the secret government, are going to precipitate some of these events?

A: No.

Q: (L) Yes. Okay, is there any more that you want to say on this? Go ahead, you have the floor. Please.

A: Ask away.

Q: (L) Well, you've said that there's a comet cluster that's coming this way. Is that still correct?

A: Yes.

Q: (L) Is this body that has been called Hale-Bopp, is this that comet cluster?

A: No.

Q: (L) Is this comet cluster that's coming, and you've indicated that it could arrive anywhere between 18 years, something like that, is that correct?

A: Maybe.

Q: (L) Now, is this something that can be seen from a great way off?

A: No.

Q: (L) Is this something that's going to impact our particular immediate location, and appear suddenly, as this comet that has flown overhead just did? Nobody saw it until a very short time ago, and all of a sudden everybody sees it?

A: The cluster is a symptom, not the focus.

Q: (V) What is the focus?

A: Wave, remember, is "realm border" crossing... what does this imply? Consult your knowledge base for Latin roots and proceed.

Q: (L) So, the Latin root of realm is regimen, which means a domain or rulership or a system for the improvement of health. Does this mean that, and as I assume we are now moving into the STO realm, now, out of the STS realm?

A: Partly.

Q: (L) And also, can I infer from this, that the comet cluster exists in the other realm?

A: Partly.

Q: (L)Well, previously, you had said that the comet cluster would come before the realm border. Which indicated that the comet...

A: Yes.

Q: (L) Well, how can something so... you said it appears to be one single large body, and that our government knows that it's on it's way, and that apparently somebody has spotted it. Which direction is it coming from?

A: Direction?

Q: (L) Well, the comet cluster. That comet cluster, is, I am assuming, a real body, in third density experience, right? A part of a real cluster of bodies in third density experience. Is that correct?

A: Cluster can approach from all directions.

Q: (L) So, can I infer from what has been said, that we are going to move into this comet cluster, as into a realm?

A: Border changes rules.

Q: (L) But if we run into the comet cluster before we cross the border, then, I mean, I would understand if we were going into the realm border first...

A: Part in part out.

Q: (L) OK, is this so-called HAARP project instrumental in any of these realm border changes, these realm changes?

A: All is interconnected, as usual.

After reading your article and discovering the list of comets with a long or even very long period, what on the Wiki they callnear-parabolic cometswith periods ranging from a 1000 years up to millions of years. I tried to order some of them in groups according to the duration of their periods.

Below is what I found using an interval of 200 years from 1000 and up to periods of 5000 years. The left column gives the range of the period of the comets in years, and the right side gives the number of discovered comets so far with periods within the given range.
1000-1200 10
1200-1400 7
1400-1600 5
1600-1800 10
1800-2000 14
2000-2200 7
2200-2400 11
2400-2600 9
2600-2800 6
2800-3000 3
3000-3200 2
3200-3400 7
3400-3600 5
3600-3800 2
3800-4000 9
4000-4200 4
4200-4400 2
4400-4600 2
4600-4800 1
4800-5000 2
If one considers that the window of reliable and comprehensive observation of comets is maybe a 20, 30, 50, 100, or 150 years one could extrapolate from the samples. If we say the window is 100 years, and there is equal distribution within the field, which is probably not the case, but if we pretend, then 100year/1000 years-100 years/1200 year is 10 % to 8.33 %. If there are 10 comets in this interval so far, then we should be able to find another about 90-130 comets in total with a period of a 1000 to 1200 years. The longer the period we consider, the smaller the presently discovered sample is relative to the length of the period. For example, if we look at the period from 3800-4000, then we find 9 comets, but our window of observation is just the same 100 years, so really we have only sampled 100/4000 of the period or about 2.5 % which is not much, but if we dare to think we have hit the average frequency then we should be able to find about 350 comets with periods of 3800-4000 years.

Zooming in on comets with periods from 3000-4000 years there was this distribution. What I have done is making the window 100 years long instead of 200 years.
3000-3100 0
3100-3200 2
3200-3300 4
3300-3400 3
3400-3500 0
3500-3600 5
3600-3700 2
3700-3800 0
3800-3900 7
3900-4000 2
4000-4100 2
4100-4200 2
一种可能性是,就像流星streams there are also comet streams, and not only the 3600 year cycle. In a meteor streams there are also the early birds followed by the peak shower. A similar pattern may play out with the comet clusters. A question is of course if there have been early birds from the 3600 year cycle and which ones, would any the ones we find in the Wiki list be among them? Or should we look into a more professional and updated list? On this page there should be a list of more than 3000 comets if one is able to configure ones system to make the program work. I couldn't do that yet, but the link is here, if anyone would like to try:Ephemerides

Another possibility is that the 3600 year cluster, if it can come from all directions, as it is said in the transcript could be the result of cosmic pulse or at least a pulse in the solar system, just like the beat of a heart. that affects the whole system. If this is the case, then trying to find patterns in the periods of discovered comets could be a waste of time. It is also possible there is a combination of different patterns like in large waves arising from constructive interference.

In the table of discovered long term comets, one will find periods like 3403179.42 years. I have not read the papers, but I would think an accuracy of a millions year long period down to the last week give and take four days is exaggerated. Indeed one could possibly question the accuracy of periods for comets that move into areas of the solar system that are little known and poorly understood, because if the distance from the Sun to Pluto varies between approximately 30-50 AU or astronomical units, each of which is 1.495978707×10^11 m. and the average distance of long term comets in the 3600 year range is around 230-250 AU on average, then these comets with orbits that are near-parabolic with eccentricities near one, move far, far beyond the orbit of Pluto. The times for the orbits would probably only be accurate if there are no major centers of gravity outside the known outer planets.

After getting this far, I found some papers that deal with the concept of comet clusters, also called comet showers, perhaps a play on meteor showers. There were also articles on mass extinctions, the role of massive stars, small stars and giant molecular clouds. I ordered them by year; it was a bit tedious, but in the process it was like opening a window to the far out areas of the Solar system from where the future comes, a bit frightening, but also grand.

Title:Comet showers and the steady-state infall of comets from the Oort cloud
Authors: Hills, J. G.
Journal: Astronomical Journal, vol. 86, Nov. 1981, p. 1730-1740.

1981 aj…86.1730 h 1730页

Davis, M., Hut, P. & Muller, R.Extinction of species by periodic comet showers.Nature308, 715–717 (1984) doi:10.1038/308715a0

Whitmire, D., Matese, J.Periodic comet showers and planet X.Nature313, 36–38 (1985) doi:10.1038/313036a0

TIDAL GRAVITATIONAL FORCES: THE INFALL OF 'NEW' COMETS AND COMET SHOWERS

Author(s): Morris, D.E.; Muller, R.A.

escholarship.org

TIDAL GRAVITATIONAL FORCES: THE INFALL OF 'NEW' COMETS AND COMET SHOWERS
1985 Author(s): Morris, D.E. Muller, R.A

Kerr, Richard A. "Periodic extinctions and impacts challenged; critics are attacking the evidence that comet showers have caused periodic extinctions."Science, vol. 227, 1985, p. 1451+.Gale OneFile: Health and Medicine, Accessed 4 Dec. 2019.

1985BAAS...17Q.690H Page 690

Title:Dynamical Evolution of Cometary Showers
Authors: Hut, P. & Weissman, P. R.
Journal: Bulletin of the American Astronomical Society, Vol. 17, p.690
Bibliographic Code: 1985BAAS...17Q.690H

Mass extinctions, crater ages and comet showers.

The authors review the underlying evidence upon which the claims of periodicity of mass extinctions and crater ages have been based and compare in detail the observed geologic record of impact events on the Earth with the paleontologic record of mass extinctions. The conclusion is that there...

ui.adsabs.harvard.edu

Mass extinctions, crater ages and comet showers.
Shoemaker, Eugene M.;Wolfe, Ruth F.

IcarusVolume 65, Issue 1, January 1986, Pages 1-12
Tidal gravitational forces: The infall of “new” comets and comet showers
Author links open overlay panelD.E.MorrisR.A.Muller
https://doi.org/10.1016/0019-1035(86)90059-X

Hut, P., Alvarez, W., Elder, W.et al. Comet showers as a cause of mass extinctions. Nature329, 118–126 (1987) doi:10.1038/329118a0

IcarusVolume 70, Issue 2, May 1987, Pages 269-288
The frequency and intensity of comet showers from the Oort cloud
Author links open overlay panelJuliaHeisler∗∗∗ScottTremaine∗∗∗†1CharlesAlcock∗∗∗1
https://doi.org/10.1016/0019-1035(87)90135-7

M. E. Bailey, D. A. Wilkinson, A. W. Wolfendale,Can episodic comet showers explain the 30-Myr cyclicity in the terrestrial record?,Monthly Notices of the Royal Astronomical Society, Volume 227, Issue 4, August 1987, Pages 863–885,Can episodic comet showers explain the 30-Myr cyclicity in the terrestrial record?

1988Obs...108....1S Page 1

SAO/NASA Astrophysics Data System (ADS)
Title:Structure of Oort's comet cloud inferred from terrestrial impact craters
Authors: Stothers, R. B.
Journal: The Observatory, vol. 108, p. 1-9 (1988)
Bibliographic Code: 1988Obs...108....1S

1991LPICo.765..199S Page 199

Title:Geological and Astronomical Evidence For Comet Impact and Comet Showers During the Last 100 Million Years
Authors: Shoemaker, E. M.
Journal: Abstracts for the International Conference on Asteroids, Comets, Meteors 1991. Held June 24-28, 1991, in Flagstaff, AZ. Sponsored by Barringer Crater Company, the Lunar and Planetary Institute, Lowell Observatory, Meteor Crater Enterprises, Inc., NASA, the Northern Arizona University, and the U. S. Geological Survey. LPI Contribution 765, published by the Lunar and Planetary Institute, 3303 Nasa Road 1, Houston, TX 77058, 1991, p.199
Bibliographic Code: 1991LPICo.765..199S

Fernández, J. (1992).Comet Showers. Symposium - International Astronomical Union, 152, 239-254. doi:10.1017/S0074180900091233 Found onComet Showers | Symposium - International Astronomical Union | Cambridge Corewhich besides an abstract lists a bibliography


IcarusVolume 116, Issue 2, August 1995, Pages 255-268
Periodic Modulation of the Oort Cloud Comet Flux by the Adiabatically Changing Galactic Tide
Author linksJohn J.MatesePatrick G.WhitmanKimmo A.InnanenMauri J.Valtonen
https://doi.org/10.1006/icar.1995.1124


Geochemical Evidence for a Comet Shower in the Late Eocene
K. A. Farley*, A. Montanari, E. M. Shoemaker†, C. S. Shoemaker
Science 22 May 1998:
Vol. 280, Issue 5367, pp. 1250-1253
DOI: 10.1126/science.280.5367.1250

Matese J.J., Whitman P.G., Whitmire D.P. (1998)Oort Cloud Comet Perihelion Asymmetries: Galactic Tide, Shower or Observational Bias?. In: Yabushita S., Henrard J. (eds) Dynamics of Comets and Asteroids and Their Role in Earth History. Springer, Dordrecht
DOIOort Cloud Comet Perihelion Asymmetries: Galactic Tide, Shower or Observational Bias?

Periodic Comet Showers, Mass Extinctions, and the Galaxy

Geologic data on mass extinctions of life and evidence of large impacts on the Earth are thus far consistent with a quasi-periodic modulation of the flux of Oort cloud comets. Impacts of large comets and asteroids are capable of causing mass extinction of species, and the records of large impact...

ui.adsabs.harvard.edu

Periodic Comet Showers, Mass Extinctions, and the Galaxy
Rampino, M. R.;Stothers, R. B.
Publication: Catastrophic Events and Mass Extinctions: Impacts and Beyond, p. 175
发布日期:2000年1月Bibcode:2000cem..conf..175R

2002ESASP.500..445M Page 445

Title:Variations of the Oort cloud comet flux in the planetary region
Authors: Mazeeva, O. A. & Emel'Yanenko, V. V.
Journal: In: Proceedings of Asteroids, Comets, Meteors - ACM 2002. International Conference, 29 July - 2 August 2002, Berlin, Germany. Ed. Barbara Warmbein. ESA SP-500. Noordwijk, Netherlands: ESA Publications Division, ISBN 92-9092-810-7, 2002, p. 445 - 448
Bibliographic Code: 2002ESASP.500..445M

2004ASPC..323..371D Page 371

SAO/NASA Astrophysics Data System (ADS)
Title:Oort Cloud Formation and Dynamics
Authors: Dones, L., Weissman, P. R., Levison, H. F., & Duncan, M. J.
Journal: Star Formation in the Interstellar Medium: In Honor of David Hollenbach, Chris McKee and Frank Shu, ASP Conference Proceedings, Vol. 323. Edited by D. Johnstone, F.C. Adams, D.N.C. Lin, D.A. Neufeld, and E.C. Ostriker. San Francisco: Astronomical Society of the Pacific, 2004., p.371
Bibliographic Code: 2004ASPC..323..371D

The Role of Giant Molecular Clouds in the Evolution of the Oort Comet Cloud

We estimated the gravitational influence of giant molecular clouds passing near the Solar system on the orbital evolution of Oort cloud comets. We performed a comparative analysis of the accuracies of the following two methods of allowance for the perturbations from giant molecular clouds: the...

link.springer.com

The Role of Giant Molecular Clouds in the Evolution of the Oort Comet Cloud
Solar System Research, 2004, Volume 38, Number 4, Page 325
O. A. Mazeeva

Assessing the Threat of Oort Cloud Comet Showers

场明星通过5000盟内的太阳能ystem once every 100 Myrs on average. During these extremely close stellar passages large numbers of Oort Cloud orbits are modified, which drastically increases the flux of long-period comets entering the inner solar system for 2-3 Myrs. We model...

ui.adsabs.harvard.edu

Publication: American Astronomical Society, DDA meeting #39, id.4.02
Pub Date: May 2008Assessing the Threat of Oort Cloud Comet Showers
Kaib, Nathan A.;Quinn, T.

Icarus Volume 214, Issue 1, July 2011, Pages 334-347

The key role of massive stars in Oort cloud comet dynamics

The effects of a sample of 1300 individual stellar encounters spanning a wide range of parameter values (mass, velocity and encounter distance) are in…

www.sciencedirect.com

The key role of massive stars in Oort cloud comet dynamics
Author links open overlay panelM.FouchardaCh.FroeschlébH.RickmancdG.B.Valsecchie
https://doi.org/10.1016/j.icarus.2011.04.012
From the abstract:

The effects of a sample of 1300 individual stellar encounters spanning a wide range of parameter values (mass, velocity and encounter distance) are investigated. Power law fits for the number of injected comets demonstrate the long range effect of massive stars, whereaslight stars affect comets mainly along their tracks.Similarly, we show that the efficiency of a star to fill the phase space region of the Oort cloud where the Galactic tides are able to inject comets into the observable region – the so-called “tidally active zone” (TAZ) – is also strongly dependent on the stellar mass.

The role of large and small cometary showers in the changes of living conditions on the Earth

1. The supremum of astrophysical problems in modern astronomy. With the introduction into service in 1974, of the largest at that time, six-meter telescope BTA at Zelenchukskaya Astrophysical Observatory (SAO) - Department of Extragalactic Research and relativistic astrophysics was established...

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The role of large and small cometary showers in the changes of living conditions on the Earth
Churyumov, K. I.;Steklov, A. F.;Vidmachenko, A. P.;Dashkiev, G. N.;Stepahno, I. V.;Steklov, E. A.;Slipchenko, A. S.;Romaniuk, Ya. O.
Materials of the International scientific-practical conference devoted to the 100th anniversary of astrophysicist I.S. Shklovskii "The problems of modern astronomy and method of its teaching." 6-8 October 2016 Glukhiv, Ukraine. - Sumy, LLC "Publishing house" Eldorado", 2016. - 128 p.

The Late Eocene Earth: Hothouse, Icehouse, and Impacts
Edited by Christian Koeberl, Alessandro Montanari
(Found on Google books)
See alsohttps://www.researchgate.net/public...se_Icehouse_and_Impacts_The_Late_Eocene_Earth

Relating this list of papers to the calculations of the distribution of the frequencies of discovered long period comets, I return to the impression that there ought to be more than one comet shower. What is it that has made the 3600 year cycle special? And coming from all sides? But perhaps there is no need to brood over the question too hard because:A: The cluster is a symptom, not the focus.

[Pierre]

Actually, after perusing this topic for a while, I've come to the idea that cometary events might well be the greatest modulator of life on Earth in general, and the rise and fall of civilizations in particular.

似乎是so, although comets would not be able to explain, I think, a Cambrian explosion of the many different species "evolving" as if they had come custom made. Such an event may connect with the influence of other densities, although rarely observed there are glitches in our reality. The title of the book you wrote was Earth Changes and the Human-cosmic Connections and it is very meaningful, but I am wondering if one could consider the order of the words differently and read them as The Human-cosmic Connection and Earth Changes, or should we rather say The Cosmic-human connection and Earth Changes.

That's an interesting question. Which came first the chicken or the egg? From what I understand it is a 2-way street. Cosmic chaos worsen the human state and the human state affects the cosmic environment.

In any case, about the Cambrian explosion, and more generally "evolution" explosions, it is peculiar to notice that the 28 million year cycle (Nemesis and its cometary swarm) triggered mass extinctions that were followed by the apparition of more complex forms of life.

We can witness this phenomenon, for example, during the Eoceone-Oligocene (E-O) boundary (ca. 33 MY BP according to official science and attributed, at least partly, to cometary bombardments) numerous Eocene species got extinct and "replaced" by the more complex Oligocene fauna.

Even more open landscapes allowed animals to grow tolarger sizesthan they had earlier in the Paleocene epoch 30 million years earlier.Marine faunas became fairly modern, as did terrestrial vertebrate fauna on the northern continents. This was probably more as a result of older forms dying out than as a result of more modern forms evolving.
Source

Similar pattern at the Cretaceous - Paleogene (K-Pt) boundary (ca. 66 MY BP according to official science and attributed by some researchers to the Chicxulub impact) where numerous Cretaceous species got extinct and "replaced" by the more complex Paleogene fauna

The Paleogene is most notable for being the time during which mammals diversifiedfrom relatively small, simple forms into a large group of diverse animals in the wake of the Cretaceous–Paleogene extinction eventthat ended the preceding Cretaceous Period.
Source

If major cometary impacts trigger jumps in terms of life complexity, the question is: "how?" One possible mechanism is cometary-borne virus. The presence of organic material is nowhypothesizedby mainstream science. And we know that viruses cantransfer DNAto their hosts.

Are major cometary impacts, the window of opportunity the "4D engineers of life" use to remove obsolete prototypes and to introduce more elaborate prototypes via the new DNA codes carried by the accompanying viruses?

Comet-borne viruses might be only one of the action mechanisms. Major cometary events might also induce energetic/radiative changes, bleedthoughs, new connections with the information field. Those modifications being potentially conducive to the "apparition" of new forms of life.

[Vulcan59]

FWIW, a research geologist,Summer Praetorius(USGS profile) posted the following on Twitter but then subsequently removed the tweet!

Link to her blogand herlisted publications.