B.2. Origin Of Earth
The following are the theories about the origin of the earth-
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Nebular Hypothesis |
Initially proposed by Immanuel Kant and later refined by Pierre-Simon Laplace, this theory suggests that the planets formed from a slowly rotating cloud of gas and dust (a nebula) associated with a young sun. |
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Binary Hypothesis |
Proposed by Chamberlain and Moulton un 1900, this theory states that a wandering star passed near the sun, and due to the gravitational interaction, a cigar-shaped extension of material was pulled from the sun’s surface, which eventually cooled and formed planets. |
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Revised the nebular hypothesis |
This is a 1950 modified version of the original nebular theory by Otto Schmidt in Russia and Carl Weizsäcker in Germany. It suggests that the sun was enveloped by a solar nebula mainly composed of hydrogen, helium, and cosmic dust, which gradually condensed to form planets. |
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Modern Theories |
Most accepted argument about the origin of the Universe is the Big Bang Theory and Edwin Hubble provided evidence that the universe is expanding. According to The Big Bang Theory, At the beginning(13.7 Billion years ago) all the matter-forming universe existed in a tiny ball (called singularity) with infinite density. This tiny ball exploded and gradually galaxies and stars were formed. |
There are a number of hypotheses regarding the origin of the Earth. Some of them are the following:A galaxy starts to form through the accumulation of hydrogen gas in the form of a very large cloud called a Nebula. These Nebula gave rise to the formation of Stars and later small rounded objects called planetesimals. These large numbers of small bodies accrete to form fewer large bodies in the form of planets.
[Image: The Big Bang Theory]