Results 261 to 270 of about 2,093,430 (321)
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International Journal of Astrobiology, 2007
AbstractMechanisms of interstellar panspermia have recently been identified whereby life, wherever it has originated, will disperse throughout the habitable zone of the Galaxy within a few billion years. This re-opens the question of where life originated.
W.M. Napier +2 more
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AbstractMechanisms of interstellar panspermia have recently been identified whereby life, wherever it has originated, will disperse throughout the habitable zone of the Galaxy within a few billion years. This re-opens the question of where life originated.
W.M. Napier +2 more
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International Astronomical Union Colloquium, 1976
The cosmogony of the planetary and satellite systems consists of understanding the physio-chemical processes leading to their formation and also trying to decide at what time and over what period their formation took place. The cosmogony of the comets require answers to not only these two questions but also as to where, in relation to the solar system,
Asoka Mendis, Hannes Alfvén
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The cosmogony of the planetary and satellite systems consists of understanding the physio-chemical processes leading to their formation and also trying to decide at what time and over what period their formation took place. The cosmogony of the comets require answers to not only these two questions but also as to where, in relation to the solar system,
Asoka Mendis, Hannes Alfvén
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A D/H ratio consistent with Earth’s water in Halley-type comet 12P from ALMA HDO mapping
Nature AstronomyIsotopic measurements of Solar System bodies provide a primary paradigm within which to understand the origins and histories of planetary materials. The deuterium-to-hydrogen (D/H) ratio, in particular, helps reveal the relationship between (and heritage
M. Cordiner +20 more
semanticscholar +1 more source
Chemical evolution of interstellar dust, comets and the origins of life.
Annals of Physics, 1989 It now appears that the chemical evolution of the pre-solar system interstellar dust ensures that a major fraction of comets is in the form of complex organic molecules at least partially of a prebiotic nature and that the submicron interstellar dust ...
J. Greenberg, N. Zhao, J. Hage
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Dynamics and potential origins of decimeter-sized particles around comet 67P/Churyumov-Gerasimenko
Astronomy and AstrophysicsContext. One of the primary goals of the European Space Agency’s Rosetta mission to comet 67P/Churyumov-Gerasimenko was to investigate the mechanisms responsible for cometary activity. Aims.
Marius Pfeifer +2 more
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Kinematics and Physics of Celestial Bodies, 2009
The paper presents a brief history of cometary cosmogony. It discusses critically the eruptive hypothesis, the hypothesis on the relict origin of comets, and the hypothesis on a genetic connection between comets and trans-Plutonian planets. Laplace’s theoretical prediction as to the capture of long-period comets by Jupiter into short-period orbits is ...
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The paper presents a brief history of cometary cosmogony. It discusses critically the eruptive hypothesis, the hypothesis on the relict origin of comets, and the hypothesis on a genetic connection between comets and trans-Plutonian planets. Laplace’s theoretical prediction as to the capture of long-period comets by Jupiter into short-period orbits is ...
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Celestial Mechanics and Dynamical Astronomy, 1992
Reasons for interest in the origin of short-period comets and the difficulties of computing their long-term dynamical evolution are reviewed. The relative advantages of a source region in an extended ‘inner core’ of the Oort cloud or a compact ‘comet belt‘ just beyond the planetary system are finely balanced, and it is premature to consider the problem
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Reasons for interest in the origin of short-period comets and the difficulties of computing their long-term dynamical evolution are reviewed. The relative advantages of a source region in an extended ‘inner core’ of the Oort cloud or a compact ‘comet belt‘ just beyond the planetary system are finely balanced, and it is premature to consider the problem
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Nature, 1973
IN so many fields of astrophysics the textbooks and the ordinary review articles have a tendency to present only the ‘generally accepted’ point of view, often not mentioning alternative theories, and even sweeping under the rug those observational facts which are adverse to the dominant view. This also applies to the theory of comets. As the arrival of
HANNES ALFVÉN, ASOKA MENDIS
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IN so many fields of astrophysics the textbooks and the ordinary review articles have a tendency to present only the ‘generally accepted’ point of view, often not mentioning alternative theories, and even sweeping under the rug those observational facts which are adverse to the dominant view. This also applies to the theory of comets. As the arrival of
HANNES ALFVÉN, ASOKA MENDIS
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2017
It was not only the physical nature of comets that so long remained a mystery. Their origin was also shrouded in obscurity, and the various hypotheses put forward to explain this were to some degree influenced by beliefs about their nature.
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It was not only the physical nature of comets that so long remained a mystery. Their origin was also shrouded in obscurity, and the various hypotheses put forward to explain this were to some degree influenced by beliefs about their nature.
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2013
Originally published in 1953, this book first sets out some observational facts about comets, then the greater part of the book accounts for their origin and explains how comet tails are formed. The text contains 34 photographs of celebrated comets, including eight of Halley's comet. A comet index is also provided.
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Originally published in 1953, this book first sets out some observational facts about comets, then the greater part of the book accounts for their origin and explains how comet tails are formed. The text contains 34 photographs of celebrated comets, including eight of Halley's comet. A comet index is also provided.
openaire +1 more source