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Definition of Nebular theory

Nebular theory Definition from Religion & Spirituality Dictionaries & Glossaries
Nebular Theory A theory of the origin of the solar system of Laplace, Herschel, and others, much in favor during the earlier part of the 19th century, but since fallen into disfavor. The hypothesis was devised to explain certain facts, especially that the planets all revolve in the same direction, that their satellites (except those of Uranus and Neptune) revolve around their primaries in this same direction, and that the planets so far as we know rotate in this same direction. The theory assumes the sun to have started as a very diffused, tenuous gas or nebula, extending much farther than its present volume. The combined influence of gravitation and of contraction by cooling resulted, in accordance with dynamic laws, in the separation of parts of the mass into rings, and these rings afterwards coalesced severally into planets; and their motions of revolution and rotation are thus according to this theory explained.
Better knowledge of the dynamic principles concerned has discredited the theory in its details; it conflicts particularly with the principle of the conservation of the moment of inertia and with the kinetic theory of gases. Moreover, the solar system is now seen to be more complex than had been supposed, the planetoids for instance having very eccentric motions.
In The Secret Doctrine Blavatsky credits the theory's authors with a great intuitional perception of certain cosmogonical facts, and to a certain extent approves the theory in its broad outline but not in its details.
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Nebular theory Definition from Encyclopedia Dictionaries & Glossaries
English Wikipedia - The Free Encyclopedia
The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System. It suggests that the Solar System formed from nebulous material. The theory was developed by Immanuel Kant and published in his Allgemeine Naturgeschichte und Theorie des Himmels ("Universal Natural History and Theory of the Heavens"), published in 1755. Originally applied to the Solar System, this process of planetary system formation is now thought to be at work throughout the Universe. The widely accepted modern variant of the nebular hypothesis is the solar nebular disk model (SNDM) or simply solar nebular model. This nebular hypothesis offered explanations for a variety of properties of the Solar System, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation. Some elements of the nebular hypothesis are echoed in modern theories of planetary formation, but most elements have been superseded.

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