A team led by Jacques Laskar from the Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE) and the Paris Observatory has released new computational results for the long-term evolution of the orbital and rotational motion of the Earth. Following Milankovitch’s theory of the paleoclimate that describes how major climatic changes on Earth are affected by astronomical events, these results have been employed to provide a new calibration of the sedimentary records over the 0 – 23.03 Myr geological period (the so-called Neogen period). Thus, Laskar et al.’s work has contributed to the definition of the new Geological Time Scale that has been adopted by the International Commission of Stratigraphy (ICS) and the International Union of Geological Sciences (IUGS). It is the first time that astronomical computations have been used to establish the ICS geological chronology over a full geological period.
Due to gravitational planetary perturbations, the orbit of the Earth slowly changes over time, as does the orientation of the planet’s spin axis. These changes induce variations of the solar radiation received on the Earth’s surface that are responsible for some of the large climatic changes of the past. The major effects of astronomical phenomena on the Earth’s climate were first described by the Serbian mathematician Milankovitch in his theory of the paleoclimate (1941). In 1976, Milankovitch’s theory was validated in the landmark work of Hays, Imbrie and Shackleton, who measured the change in continental ice volume over time through the variation of the isotopic ratio of oxygen in marine sediments. The succession of the Ice Ages that occurred during the Pleistocene epoch (between 10 000 yrs and 1.8 million yrs (Myr) ago) has been shown to be related to the periodic changes of the Earth’s orbit and rotational parameters. Since then, the Milankovitch theory has been confirmed: the variation of the Earth’s orbital parameters regulates some of the major changes in the Earth’s climate.
Therefore, the computation of the evolving planetary orbits is of major interest to those who try to understand the past and future of the Earth’s climate. Such computations, provided by astronomers, were used by Milankovitch to establish his theory. Indeed, he used the orbital computations made in 1856 by Le Verrier, former director of the Paris Observatory and famed discoverer of Neptune in 1846. Since then, the Paris Observatory’s teams have continued to be involved in the computation of the variations of planetary orbits over an extended time span. In addition to providing tools for the understanding of the Earth’s major climatic changes, computations of planetary orbits make it possible to refine the geological time scale used by geologists. A fundamental step to understanding the Earth’s past chronology is the establishment of a complete, precise time scale for geological records. The Geologic Time Scale depends on two aspects of the dating of the records. First, the sedimentary records that are collected worldwide must be linked together through significant events, such as the appearance/disappearance of living species or the paleomagnetic reversals. The sedimentary records can then be associated to a relative timescale.
Jennifer Martin | alfa
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The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
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15.11.2017 | Event News
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21.11.2017 | Physics and Astronomy
21.11.2017 | Physics and Astronomy
21.11.2017 | Life Sciences