Are periodic mass extinctions driven by a distant solar companion?

Whitmire, Daniel P.; Jackson, A. A.

doi:10.1038/308713a0

Cited by 186 publications

(95 citation statements)

References 26 publications

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“…The periodicity detected by Alvarez & Muller (1984) in the terrestrial impact crater record has been suggested to be caused by regular "comet showers" from the Oort cloud towards the inner solar system (Davis et al 1984;Whitmire & Jackson 1984;Rampino & Stothers 1984;Schwartz & James 1984). However, direct evidence for such comet showers is lacking.…”

Section: Origin Of Periodicitymentioning

confidence: 97%

“…In the same volume of Nature, two theories on the possible astronomical process capable of triggering periodic comet showers from the Oort cloud were presented. Davis et al (1984) and Whitmire & Jackson (1984) suggested that an unseen solar companion "Nemesis" causes periodic perturbances to the Oort cloud, and Rampino & Stothers (1984) and Schwartz & James (1984) argued for perturbances caused by the oscillation of the Solar System through the Galactic plane. For a quarter of a century, evidence that confirms the existence of real periodicity in these catastrophic events has been published, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Detection of real periodicity in the terrestrial impact crater record: quantity and quality requirements

Lyytinen

Jetsu

Kajatkari

et al. 2009

A&A

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Aims. To determine the quantity and quality requirements for the terrestrial impact crater data which would allow reliable detection of real periodicity. Methods. Artificial impact crater data samples of different size and accuracy are simulated. Erosion is considered, as well as the effect of the unknown ratio between periodic and aperiodic impacts. The probabilities for detecting real and false periodicities are solved with the Rayleigh test from these simulated data.Results. Reliable detection of real periodicity is currently impossible -unless all impacts on Earth have been periodic.

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Section: Origin Of Periodicitymentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Detection of real periodicity in the terrestrial impact crater record: quantity and quality requirements

Lyytinen

Jetsu

Kajatkari

et al. 2009

A&A

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“…Existem também modelos astrofísicos periódi-cos alternativos para a hipótese de Shiva, um deles envolvendo uma estrela binária companheira do Sol, chamada de Nemesis 35 , ou Estrela X, ou ainda Estrela da Morte (Whitmire & Jackson 1984, Davis et al 1984; ou um décimo planeta, o Planeta X, orbitando além de Netuno (Whitmire & Matese 1985), ambos supostamente capazes de perturbar a rota de cometas a cada 28 milhões de anos. Todavia, Nêmesis, na mitologia grega, é a deusa que personifica a retribuição, destino, equilíbrio e vingança divina.…”

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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“…Sun in a distant, eccentric, 26 x 10 6 year period orbit with its perihelion deep in the Oort cloud (Whitmire and Jackson, 1984;Davis et al, 1984); 2) a 10th planet circulating in a highly inclined, precessing orbit at about 150 AU from the Sun, at the inner edge of the inner Oort cloud (Whitmire and Matese, 1985); or 3) the solar system's epicyclic motion above and below the galactic plane with a half-period of 32 to 33 x 10 6 years, with GMC encounters at galactic plane crossings (Rampino and Stothers, 1984). The apparent coincidence between galactic plane crossings by the solar system and terrestrial extinction boundaries had been pointed out originally by Innanen et al (1978).…”

Section: Temporal Variations In the Cometary Fluxmentioning

confidence: 99%

Dynamical History of the Oort Cloud

Weissman¹

1989

International Astronomical Union Colloquium

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ABSTRACT. Dynamical studies during the past decade have resulted in an almost explosive increase in our understanding of the Oort cloud of comets, which surrounds the solar system. Cometary orbits in the cloud evolve under the complex interaction of stellar, galactic, and giant molecular cloud perturbations, as well as planetary and nongravitational perturbations when the orbits re-enter the planetary region. Evidence has continued to build for a dense, inner Oort cloud of comets which acts as a reservoir to replenish the outer cloud as comets there are stripped away. A ring of comets beyond the orbit of Neptune, which may be the source of the short-period comets, is also likely. Both the estimated number and mass of comets in the Oort cloud have grown such that the total mass may be comparable to the mass of the planets. Temporal variations in the flux of comets from the Oort cloud into the planetary region by a factor of 50% are typical, and by factors of 20 to 200 are possible. The most intense cometary "showers" may have serious implications for biological extinction events on Earth as well as for the impact history of planets and satellite systems. Comets in the Oort cloud are processed by galactic cosmic rays, heated by nearby supernovae, eroded by interstellar dust impacts, and disrupted by mutual collisions (in the inner cloud). A detailed estimate of the Oort cloud's dynamical history is not possible because of the inability to reconstruct the Sun's varying galactic motion over the history of the solar system, and because of uncertainty over where comets actually formed. However, it is likely that a substantial fraction of the original Oort cloud population has been lost to interstellar space. We are approaching the time when Oort clouds around other stars may be detectable, though searches to date have so far been negative.

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Are periodic mass extinctions driven by a distant solar companion?

Cited by 186 publications

References 26 publications

Detection of real periodicity in the terrestrial impact crater record: quantity and quality requirements

Detection of real periodicity in the terrestrial impact crater record: quantity and quality requirements

Ciclos climáticos e causas naturais das mudanças do clima

Dynamical History of the Oort Cloud

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