The “Shiva Hypothesis”: Impacts, mass extinctions, and the galaxy

Rampino, Michael R.; Haggerty, Bruce M.

doi:10.1007/bf00117548

Cited by 33 publications

(19 citation statements)

References 78 publications

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“…Further noise may be due to the crossing of the galactic plane being not sharply defined: the precise timing may be affected by varying density of plane material and by individually encountered stars and molecular clouds. Recent impacts have been recognized at approximately 95, 65, 35, and 2-3 Myr ago (Rampino and Haggerty, 1996). Even with the last one already 2-3 Myr behind us, its effects may still be with us, still be present in Table 1 (Valtonen et al, 1995).…”

Section: Studies Of Periodicity For Long-period Cometsmentioning

confidence: 98%

A review of comet and asteroid statistics

Gehrels

2014

Earth Planet Sp

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The statistics of Earth-approaching asteroids are first summarized, and an enhanced frequency of objects smaller than 100 meters is noted. Superposed on these random hazards may be a periodic one of new comets due to galactic tides of the Oort Cloud with a period of 26-36 Myr (Rampino, 1998). New asteroids and comets are being found evermore frequently because new telescope-and-detector systems are coming on line. These are intended primarily for the discovery of dangerous objects, but a beginning has been made with the study of statistics of main-belt asteroids. In addition to trans-Neptunian objects, cis-Neptunian "Centaurs" are recognized, which may be a link in the evolution of short-period comets and thereby contribute to the flux of Earth approachers. With the new equipment coming on line, we are beginning to see that the global hazard will be mostly quantified within a few decades. We do see a shortage in astrometric follow up fainter than about the 20th magnitude.

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Section: Studies Of Periodicity For Long-period Cometsmentioning

confidence: 98%

A review of comet and asteroid statistics

Gehrels

2014

Earth Planet Sp

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“…In one of them extinctions (particularly the large ones) result from external (non-biotic) events such as meteorite impacts, volcanic eruptions or changes in the magnetic field of Earth [52] [15] [50] [51]. This view has an obvious interest and relevance.…”

Section: Macroevolution and Extinctionmentioning

confidence: 99%

Modelling macroevolutionary patterns: An ecological perspective

Solé

Biological Evolution and Statistical Physics

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Abstract. Complex ecosystems display well-defined macroscopic regularities suggesting that some generic dynamical rules operate at the ecosystem level where the relevance of the single-species features is rather weak. Most evolutionary theory deals with genes/species as the units of selection operating on populations. However, the role of ecological networks and external perturbations seems to be at least as important as microevolutionary events based on natural selection operating at the smallest levels. Here we review some of the recent theoretical approximations to ecosystem evolution based on network dynamics. It is suggested that the evolutionary dynamics of ecological networks underlie fundamental laws of ecology-level dynamics which naturally decouple micro from macroevolutionary dynamics. Using simple models of macroevolution, most of the available statistical information obtained from the fossil record is remarkably well reproduced and explained within a new theoretical framework.

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“…Segundo Matese et al (1994) e Rampino & Haggerty (1996), a melhor estimativa do próximo evento de grande impacto é ocorrer dentro dos próximos 600 mil anos. Todavia, considerando o desvio padrão do modelo de Matese et al (1994) dos picos nos fluxos de cometas oriundos da nuvem de Oort, o valor com o intervalo de confiança para o próximo evento de impacto é de 0,6 ± 1,7 milhões de anos, ou seja, já iniciou há 1,1 milhões de anos atrás e se estende até os próximos 2,4 milhões de anos.…”

Section: Guerras Nuclearesunclassified

Ciclos climáticos e causas naturais das mudanças do clima

et al. 2018

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TerraeDid atic a IntroduçãoA presente histeria sobre aquecimento global -com a previsão apocalíptica de fusão das calotas de gelo polar, inundação de cidades costeiras e desertificação de zonas produtoras de alimentos -não ajuda os cidadãos a compreender as forças reais e complexas que moldam o clima da Terra (Hecht 1993(Hecht -1994.Tentar entender o clima tem sido prática de sobrevivência desde os primórdios da humanidade. Inegavelmente, compreender o momento ideal do plantio e da colheita fez parte das técnicas da agricultura primitiva que permitiram ao homem a transição do nomadismo para o sedentarismo. Assim, a partir da constatação da óbvia alternância entre o dia e a noite, da observação das fases da Lua, da dedução das estações do ano, foi-se descobrindo a estreita relação entre esses fenômenos (cíclicos e de origem astronômica) com as alterações do clima na Terra (também de caráter periódico). ABSTRACT:The periodic nature of climate changes on the Earth can be explained in terms of a limited number of terrestrial and astronomical factors. In annual/daily scales, the climate varies according to the Earth's revolution and rotation. Medium term climate cycles (decades/centuries/millennia) are related to changes in solar radiation caused by the influences of major planets of the Solar System. Oceanic oscillations (decadal order) are possibly caused by the planetary and lunar influences. Long term climate cycles (tens and hundreds of thousand years) are caused by variations in the parameters of Earth's orbit (eccentricity, obliquity and precession). Impact events of large bodies on the planet and mass extinction arise from supercycles (tens of millions of years) caused by the vertical oscillation of the solar system relative to the galactic plane. Tectonics, volcanism and the evolution of supercontinents exhibit supercycles (hundreds of million years) induced by the Solar System movement around the Milky Way center and by the cosmic rays variation. Astronomical factors permeate virtually all the climate cycles orders, acting directly or indirectly in many bio-geo-oceanic-atmospheric processes. It is concluded that the Earth's climate is characterized by cycles astronomically controlled by the Moon, the Sun, the planets, the Solar System and even the Galaxy. Ciclos climáticos e causas naturais das mudanças do clima

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The “Shiva Hypothesis”: Impacts, mass extinctions, and the galaxy

Cited by 33 publications

References 78 publications

A review of comet and asteroid statistics

A review of comet and asteroid statistics

Modelling macroevolutionary patterns: An ecological perspective

Ciclos climáticos e causas naturais das mudanças do clima

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