Theories related to Origin of Earth/Solar System
The second school of thought i.e., the second body hypothesis assume that the solar system originated as the result of force created by the accidental interference of another celestial object. Because the latter hypothesis is generally presumed that another star passed close to the sun, these have also been called the two star theories.
Though we cannot be certain as to which of this hypothesis is correct yet the common principle of this hypothesis is that the sun is the mother of the earth.
1. Kant's Hypothesis
This perhaps is the first explanation which was put forward by Kant (in 1775). He believed that the planetary system had been formed by the condensation of nebula which was in a hot gaseous state in its early stage.
Drawback:
It was soon felt after the kant's hypothesis that it had got nothing to do with reality, as it could not explain how the Earth was formed, its only important is that kant by putting this hypothesis drew the attention of the scientist and pioneeved the way of modern research to explain the origin of the earth.
2. Nebular Hypothesis
In 1796, a French mathematician Laplace develop the theory more fully and expressed it scientifically interestingly enough Laplace was unknown of the earlier work done by the kant and still both arrived at similar conclusion quiet independently.
This hypothesis assumes the existence of large globular mass of gas slowly rotating through space. This gaseous mass was called as Nebula, gradually became smaller in response to its inherent gravitational pull.
The nebula in its early history was bigger than the entire planetary system and was rotating in space. Due to cooling and contraction outer parts move faster than the inner one.
Eventually the outermost part of nebula rotated so rapidly that the C.F. caused a ring of gas or matter to separated from sinkage nebula at the equator.
These rings slowly got condensed to form the planets (including earth) and the central mass became the sun.
This hypothesis was considered to be the most reliable scientific explanation in the past two centuries but in the 20th century, the other scientific explanation have been put forward which appear to be more reliable than the nebular hypothesis.
Drawback:
1. The major drawback of nebular hypothesis is that now it is being felt that this hypothesis fails to explain the principle of conservation of angular momentum in the solar system.
According to this principle the sun which is the parent planet of our solar system would have been even rotate in now at a great speed and would have been ready to give rise to another ring to form another planet which does not appear true, because the sun is rotating too slowly in comparison to the planets.
For this mechanism to have worked, if this system of origin of the solar system actually takes place in the sun should have been having the greatest angular momentum, because it is the most massive element of the solar system and lies at the centre of the system.
The factual position on the other hand is quite contrary as the sun is having only 2% of the total angular momentum.
2. Another objection to this theory is that it is most probable that such detached rings of gas would have dissipated in space rather than getting condensed into solid planets.
3. Planetesimal Hypothesis
In 1904,
-American geologist (Chamberlain)
-American astronomical (Moulten)
have proposed this theory
This theory assumes the existence of two star in space the very beginning the sun was just considered to be one of these two stars existing before the formation of planet at some time in the remote past an Intruder star passed by the sun, by exerting a gravitational force on the sun (or huge tides were raised in the sun) strong enough to pull masses of solar material from opposite sides of the sun.
This detached material was dragged along in the direction of movement of the passing star and later got cold and condensed into solid particles called planetesimals, each pursuing its own orbit around the sun. The largest of these planetesimals acted as nuclei that attracted other planetesimals and the planets eventually grow to their parent size.
Still other knots or clusters of planetesimals located near the cluster from which planets were formed, and formed the satellites in the same fashion.
According to this hypothesis the angular momentum of the planet was derived from pull of the passing star.
Drawback:
1. But major objection to this idea is that such a sideways motion of planets could not possibly be produced by the passing star because when it was about 150 million kilometre away from the sun it would be moving almost away from it.
2. A lot of astronomers believe that it is highly unlikely that another star could have arts so close to the sun and even if such a near miss had occurred it is doubtful that the intruders star could have generated sufficient lateral trust to get the detailed solar masses in motion in orbit instead it is more likely that such masses would have fallen back in the sun.
4. Jean's Tidal Hypothesis
Planetesimal hypothesis was modified by British astronomer named Jean (in 1925). He believed that our solar system had been formed as a result of passage of another star very close to sun. Under the influence of attraction of this task some gaseous filament was formed out from the sun. This filament was dragged by the star for some distance in space and was left behind when the pull was decreased. Its condensation give rise to all the planets of our solar system which kept rotating around the sun.
Drawback:
1. It fails to explain certain fundamental such as passing star cannot possibly import the proper angular momentum to the gaseous filament.
2. According to the assumed conditions that torn out material being at exceedingly very high temperature would have easily been dispersed into the space instead of forming planets by condensation.
5. The Buffon's Theory
According to buffon's the sun and the passing star colloided is gathered during their individual movement in the space. As a result of this collision and unstable gaseous material was detached and planets were formed in the same way in the tidal hypothesis.
Drawback:
1. It fails to explain certain fundamental such as passing star cannot possibly import the proper angular momentum to the gaseous filament.
2. According to the assumed conditions that torn out material being at exceedingly very high temperature would have easily been dispersed into the space instead of forming planets by condensation.
(Same as tidal hypothesis)
6. The Protoplanet Hypothesis on Turbulent Hypothesis
Latest and widely accepted.
First proposed in 1944 by a German Physicist (Weizeacker). In the same year his views were also supported with some modification of course by the Soviet Mathematician (Smith). Later in 1951 an American Scientist (Kviper) modified this theory and thus finally enunciated the protoplanet theory.
This theory assume that in the very beginning there was a hot gaseous nebular mass, rapidly rotating in space.
This nebula got collected some dust and gases due to gravitational attraction thus forming a disc type cloud of dust and gas. Because of its rotating nature this nebular disc developed large whirlpools or vortexes at various places. Ultimately these eddies got separated from the nebula mass. These independent eddies also contain whole system of smaller eddies. This eddies might then have collected the surrounding dusty material by gravitational attraction thus forming swirls of dust and gas, called Protoplanets.
In fact it is believed that 9 such protoplanets for each of the present day planets were formed in this way. These original protoplanet were much larger than the finished planet. Smaller eddies then got developed inside some of the larger eddies, giving rise to spinning disc that became the satellites are moons of the planets. This theory far from complete and origin of the solar system and that of the earth still largely in the realm of speculation.
Ty bruh
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