110 lines
6.9 KiB
Plaintext
110 lines
6.9 KiB
Plaintext
ÜÜÜÜÜÜÜÜÜÜÜÜÜ ÜÜÜ ÜÜÜÜ
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ÜÛÛÛÛÛÛÛÛßÛßßßßßÛÛÜ ÜÜßßßßÜÜÜÜ ÜÛÜ ÜÛÛÛÛÛÛÛÛÜÜÜÜÜÛßß ßÛÛ
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ßÛÛÛÛÛÛÛÛÛÛÛÛÛÛÜ ßÛÛ ÜÛÛÛÜÛÛÜÜÜ ßÛÛÛÛÜ ßÛÛÛÛÛÛÛÜÛÛÜÜÜÛÛÝ Ûß
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ßßßÛÛÛÛÛÛÛÛÛÛÜ ÞÝ ÛÛÛÛÛÛÛÛÛÛÛßßÛÜÞÛÛÛ ÛÛÛÛÛÜ ßßÛÛÛÞß
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Mo.iMP ÜÛÛÜ ßÛÛÛÛÛÛÛÝÛ ÞÛÛÛÛÛÛÛÛÛ ÞÛÛÛÛ ÞÛÛÛÛÛÝ ßÛß
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ÜÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛÝ ÛÛÛ ÛÛÛÛÛÛ
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ÜÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛ ÞÛÛÛÛÛÛÛÛ ß ÞÛÛÛÛÛÛÜ ÜÛ
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ÜÛÛÛÛÛÛÛÝ ÛÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÞÛÛÛÛÛÛÛÛÛß
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ÜÛßÛÛÛÛÛÛ ÜÜ ÛÛÛÛÛÛÛÛÝ ÛÛÞÛÛÛÛÛÝ ÞÛÛÛÛÛÛßß
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ÜÛßÛÛÛÛÛÛÜÛÛÛÛÜÞÛÛÛÛÛÛÛÛ ÞÛ ßÛÛÛÛÛ Ü ÛÝÛÛÛÛÛ Ü
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ÜÛ ÞÛÛÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛ ßÛÜ ßÛÛÛÜÜ ÜÜÛÛÛß ÞÛ ÞÛÛÛÝ ÜÜÛÛ
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ÛÛ ÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛÛÜ ßÛÜ ßßÛÛÛÛÛÛÛÛÛß ÜÜÜß ÛÛÛÛÜÜÜÜÜÜÜÛÛÛÛÛß
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ßÛÜ ÜÛÛÛß ßÛÛÛÛÛÛÛÛÛÛÜ ßßÜÜ ßßÜÛÛßß ßÛÛÜ ßßßÛßÛÛÛÛÛÛÛßß
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ßßßßß ßßÛÛß ßßßßß ßßßßßßßßßßßßß
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ARRoGANT CoURiERS WiTH ESSaYS
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Grade Level: Type of Work Subject/Topic is on:
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[x]6-8 [ ]Class Notes [Origins of the Solar ]
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[ ]9-10 [ ]Cliff Notes [System ]
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[ ]11-12 [x]Essay/Report [ ]
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[ ]College [ ]Misc [ ]
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Dizzed: o4/95 # of Words:889 School: ? State: ?
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ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>Chop Here>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ
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ORIGIN OF THE SOLAR SYSTEM
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For more than 300 years there has been serious scientific discussion
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of the processes and events that led to the formation of the solar system.
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For most of this time lack of knowledge about the physical conditions in
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the solar system prevented a rigorous approach to the problem.
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Explanations were especially sought for the regularity in the directions of
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rotation and orbit of objects in the solar system, the slow rotation of the
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Sun, and the Titius-Bode law, which states that the radii of the planetary
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orbits increase in a regular fashion throughout the solar system. In a
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similar fashion, the radii of the orbits of the regular satellites of
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Jupiter, Saturn, and Uranus increase in a regular manner. In modern times
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the slow rotation of the Sun has been explained as resulting from the
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deceleration of its angular motion through its magnetic interaction with
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the outflowing solar wind, so that this feature should not have been
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considered a constraint on theories of the origin of the solar system.
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The many theories concerning the origin of the solar system that have
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been advanced during the last three centuries can be classified as either
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dualistic or monistic. A common feature of dualistic theories is that
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another star once passed close to the Sun, and tidal perturbations between
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the two stars drew out filaments of gas from which the planets condensed.
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Theories of this type encounter enormous difficulties in trying to account
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for modern information about the solar system, and they have generally been
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discarded. By contrast, monistic theories envisage a disk of gas and dust,
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called the primitive solar nebula, that formed around the Sun. Many of
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these theories speculate that the Sun and the planets formed together from
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the primeval solar nebula. A photograph taken in 1984 of a nearby star,
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Beta Pictoris, appears to show a solar system forming in this way from a
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disk of surrounding material.
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The large amount of activity that has taken place in the last 20 years
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in the renewed exploration of the solar system has also provided a great
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impetus for renewed studies of the origin of the system. One important
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component of this research has been the detailed studies of the properties
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of meteorites that has been made possible by modern laboratory
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instrumentation. The distribution and abundance of the elements within
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different meteoritic mineral phases has provided much information on the
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physical conditions present at the time the solar system began to form.
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Recent discoveries of anomalies in the isotopic compositions of the
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elements in certain mineral phases in meteorites promise to give
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information about the local galactic interstellar environment that led to
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the formation of the solar system. Investigations of the properties of
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other planets has led to the new science of comparative planetology, in
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which the differences observed among the planets not only lead to a better
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understanding of the planets, but also pose precise new questions
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concerning the mechanisms by which the planets may have been formed.
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Studies of the stars within our galaxy have shown that the age of our
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galaxy is much greater than the age of the solar system. Therefore,
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processes observed in the formation of stars within our galaxy today are
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likely to be found relevant to the formation of our solar system. Stars
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appear to form in groups or associations, as a result of the gravitational
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collapse of clouds of gas and dust in the interstellar medium. Modern
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monistic theories envisage the gas and dust in the primitive solar nebula
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to be the collapsed remnant of a fragment of an interstellar cloud.
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There has been much discussion of how the planets might have formed
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from the primeval solar nebula. In recent years attention has focused on
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the possibility that two types of gravitational instabilities might have
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played an important role in this process. One type is a gravitational
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instability in the gas of the primitive solar nebula, from which there
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would be formed a giant gaseous protoplanet. From the evolution of such
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protoplanets there could arise, in the outer solar system, the giant
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planets that are observed today. In the inner solar system, the possibility
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exists that giant gaseous protoplanets formed rocky cores at their centers,
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which survived the stripping away of the gaseous envelopes caused by
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gravitational and thermal forces from the growing Sun.
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The other form of gravitational instability involves the condensed
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materials in the solar nebula. Small dust particles that may have been
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present in the gas of the solar nebula could be expected to settle toward
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the midplane of the nebula if the gas were not subject to extensive
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turbulent churning. Gravitational instabilities acting on a thin dust layer
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might have formed bodies ranging from tens to hundreds of kilometers in
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radius. Collisions among these bodies may have played a major role in
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accumulations of material to form the planets.
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It must be stressed that all theories of the origin of the solar
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system currently being formulated respond to and are limited by the rapid
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accumulation of facts about planetary bodies within the solar system.
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Because of the rapid rate of progress in such studies, it is generally
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recognized that such theories are preliminary and simplified, so that ideas
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and theories in this area of research can be expected to continue to evolve
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rapidly.
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