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The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems). It suggests the Solar System is formed from gas and dust orbiting the Sun which clumped up together to form the planets.
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 most widely accepted model of planetary formation is known as the nebular hypothesis.This model posits that, 4.6 billion years ago, the Solar System was formed by the gravitational collapse of a giant molecular cloud spanning several light-years.
Given this, Crick and Orgel argued that experimental evidence required to validate one theory over the other was lacking. [47] That being said, evidence strongly in favor of abiogenesis over panspermia exists today [ citation needed ] , whereas evidence for panspermia, particularly directed panspermia, is decidedly lacking.
The atmosphere is nebular. Possible early oceans or bodies of liquid water. The Moon is formed around this time probably due to a protoplanet's collision into Earth. Archean: 4,000–2,500 Prokaryote life, the first form of life, emerges at the very beginning of this eon, in a process known as abiogenesis.
The Chamberlin–Moulton planetesimal hypothesis was proposed in 1905 by geologist Thomas Chrowder Chamberlin and astronomer Forest Ray Moulton to describe the formation of the Solar System. It was proposed as a replacement for the Laplacian version of the nebular hypothesis that had prevailed since the 19th century.
This stood in contrast to what he called the single ruling theory, which encouraged scientists to find supporting data and not challenge it with difficult tests. The paper is considered a landmark [ 5 ] on the scientific method, was an inspiration for the approach called strong inference , and was reprinted in 1965.
A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, H 2), and the formation of H II regions.