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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]
While the broad picture of the nebular hypothesis is widely accepted, [33] many of the details are not well understood and continue to be refined. The refined nebular model was developed entirely on observations of the Solar System because it was the only one known until the mid-1990s.
This hypothesis is now considered unlikely, since the asteroid belt has far too little mass to have resulted from the explosion of a large planet. In 2018, a study from researchers at the University of Florida found the asteroid belt was created from the fragments of at least five or six ancient planetary-sized objects instead of a single ...
These are lists of planets.A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk.
In astronomy or planetary science, the frost line, also known as the snow line or ice line, is the minimum distance from the central protostar of a solar nebula where the temperature is low enough for volatile compounds such as water, ammonia, methane, carbon dioxide and carbon monoxide to condense into solid grains, which will allow their accretion into planetesimals.
Although denser than the space surrounding them, most nebulae are far less dense than any vacuum created on Earth (10 5 to 10 7 molecules per cubic centimeter) – a nebular cloud the size of the Earth would have a total mass of only a few kilograms.
[38] [39] The currently favored formation mechanism is that of the nebular hypothesis, which states that comets are probably a remnant of the original planetesimal "building blocks" from which the planets grew. [40] [41] [42] Astronomers think that comets originate in both the Oort cloud and the scattered disk. [43]