Nebular hypothesis

The solar nebula is in the cosmogony a mist of much gas and relatively little dust from which the solar system was formed. The hypothesis of such a primordial cloud was first introduced in 1755 by Immanuel Kant in his work, Universal Natural History and Theory of the Heavens. He has assumed that has prevailed in this mist through the interaction of its particles with time an initially somewhat prevalent sense of circulation and the primordial cloud therefore more pronounced flattened and rotated. This is confirmed by the modern theory of star formation.

Historical nebular

In 1796 Pierre- Simon Laplace presented regardless of retaining relatively similar model. It appeared in the last volume of his five- volume work exposure du du monde systems ( representation of the world system ) and is today known as the nebular hypothesis. Laplace was based on an existing Sun whose heated atmosphere took lenticular shape for analogous reasons. In the course of cooling and corresponding compression of the gas envelope prevailed in their outermost region with time, the centrifugal force, and it dissolved successively more gas rings from which have condensed further, to the planet.

The cosmogony of Kant and the nebular hypothesis of Laplace are often simply referred to collectively as Kant -Laplace theory.

Objections to the Kant -Laplace theory

During the late 19th century, the views of Kant and Laplace by James Clerk Maxwell were criticized. He argued that if the matter of the known planets would have been once distributed in the form of discs around the sun, the forces of differential rotation would have prevented the condensation of individual planets in the outer region. Another objection was that the sun has less angular momentum than they should have according to the theory. For several decades, most astronomers preferred the theory of near-miss: The planets were caused by another star to the sun approached. Here are the mutual tidal forces large amounts of matter taken out of the sun and the other stars, which are then condensed into planets.

Also, the theory of near- collision there were objections and during the 1940s the Kant -Laplace theory was modified so that it was generally believed. This revised version of the original mass of the protoplanet was rated higher and the lack of angular momentum has been explained by the effect of magnetic forces.

• Solar system