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The widely accepted modern variant of the nebular theory is the solar nebular disk model (SNDM) or solar nebular model. [1] It 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.
In cosmogony, the nebular hypothesis is the most widely accepted model explaining the formation and evolution of the Solar System. It was first proposed in 1734 by Emanuel Swedenborg . Originally applied only to our own Solar System , this method of planetary system formation is now thought to be at work throughout the universe .
The nebular hypothesis says that the Solar System formed from the gravitational collapse of a fragment of a giant molecular cloud, [9] most likely at the edge of a Wolf-Rayet bubble. [10] The cloud was about 20 parsecs (65 light years) across, [ 9 ] while the fragments were roughly 1 parsec (three and a quarter light-years ) across. [ 11 ]
The refined nebular model was developed entirely on observations of the Solar System because it was the only one known until the mid-1990s. It was not confidently assumed to be widely applicable to other planetary systems , although scientists were anxious to test the nebular model by finding protoplanetary discs or even planets around other ...
It was proposed as a replacement for the Laplacian version of the nebular hypothesis that had prevailed since the 19th century. The hypothesis was based on the idea that a star passed close enough to the sun early in its life to cause tidal bulges to form on its surface, which along with the internal process that leads to solar prominences ...
The word theory in "the theory of evolution" does not imply scientific doubt regarding its validity; the concepts of theory and hypothesis have specific meanings in a scientific context. While theory in colloquial usage may denote a hunch or conjecture, a scientific theory is a set of principles that explains an observable phenomenon in natural ...
Historically, "information literacy" has largely been seen from the relatively top-down, organisational viewpoint of library and information sciences. [17] However the same term is also used to describe a generic "information literacy" skill. [17] The modern digital age has led to the proliferation of information spread across the Internet.
Firstly, the Kant-Laplace Nebular theory of solar system and planetary formation was gaining favor, and implied that when the Earth first formed, the surface conditions would have been inhospitable to life as we know it. This meant that life could not have evolved parallel with the Earth, and must have evolved at a later date, without ...