Astronomy

Origin of the Solar System (III)

Origin of the Solar System (III)

Since 1900, the nebular hypothesis to explain the formation of the Solar System lost so much strength that the idea of ​​any evolutionary process seemed discredited forever. The stage was set for the resurrection of a catastrophic theory.

In 1905, two wise Americans, Thomas Chrowder Chamberlin and Forest Ray Moulton, proposed a new one, which explained the origin of the planets as the result of a quasi-collision between our Sun and another star.

This encounter would have torn gaseous matter from both suns, and the clouds of material abandoned in the vicinity of our Sun would later have condensed into small "planetesimals", and these, in turn, on planets. This is the planetesimal hypothesis.

Regarding the problem of angular momentum, British scientists James Hopwood Jeans and Harold Jeffreys proposed, in 1918, a way hypothesis, suggesting that the gravitational attraction of the Sun that passed next to ours would have communicated to the gas masses a kind of lateral impulse (giving them "effect", so to speak), which is why it would have imparted an angular momentum to them.

If such a catastrophic theory was true, it could be assumed that planetary systems had to be very scarce. The stars are so widely spaced in the Universe, that stellar collisions are 10,000 times less common than those of supernovae, which, on the other hand, are not, in fact, very frequent. As calculated, in the life of the Galaxy there has only been time for ten meetings of the type that could generate solar systems according to this theory.

However, these initial attempts to assign a role to catastrophes failed, when subjected to the verification of mathematical analyzes. Russell showed that, in any of these quasi-collisions, the planets should have been located thousands of times farther from the Sun than they really are. On the other hand, attempts to save the theory were unsuccessful by imagining a series of real collisions, rather than quasi-collisions.

During the decade that began in 1930, Lyttleton speculated about the possibility of a collision between three stars, and, later, Hoyle suggested that the Sun had a companion, which became a supernova and left the planets as the last legacy. However, in 1939, the American astronomer Lyman Spitzer showed that a material projected from the Sun, in any circumstance, would have such a high temperature that it would not condense on planetesimals, but would expand in the form of a dim gas. That seemed to end the whole idea of ​​catastrophe.

Despite this, in 1965, a British astronomer, MM Woolfson, insisted on the subject again, suggesting that the Sun could have thrown its planetary material from a cold, very diffuse star, so that they should not have intervened necessarily extreme temperatures.

And so, once the planetesimal theory was over, astronomers returned to evolutionary ideas and reconsidered Laplace's nebular hypothesis.

By then he had greatly expanded his vision of the Universe. The new question that was raised was that of the formation of galaxies, which naturally needed greater clouds of gas and dust than those supposed by Laplace as the origin of the Solar System. And it was clear that such huge sets of matter would experience turbulence and be divided into whirlpools, each of which could be condensed into a different system.

In 1944, the German astronomer Cari F. von Weizsácker carried out a thorough analysis of this idea. He calculated that in the greater eddies there would be enough matter to form galaxies. During the turbulent contraction of each eddy, smaller eddies would be generated, each of them large enough to originate a Solar System, with one or more suns.

In the limits of our solar swirl, those smaller eddies could generate the planets. Thus, in the unions in which these eddies were, moving against each other as gears of a gearshift, dust particles would collide and melt, first the planetesimals and then the planets.

Weizsácker's theory did not resolve the questions about the angular momentum of the planets on its own, nor did it provide more clarifications than the much simpler version of Laplace. The Swedish astrophysicist Hannes Alfven included in his calculations the magnetic field of the Sun. When the young Sun turned rapidly, his magnetic field acted as a moderating brake of that movement, and then the angular momentum would be transmitted to the planets.

Based on this concept, Hoyle elaborated Weizsácker's theory again in such a way that it - once modified to include the magnetic and gravitational forces - remains, it seems, the one that best explains what the reality really was. origin of the solar system.

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