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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]
Similar nebulae not illuminated by stars do not exhibit visible radiation, but may be detected as opaque clouds blocking light from luminous objects behind them; they are called dark nebulae. [ 25 ] Although these nebulae have different visibility at optical wavelengths, they are all bright sources of infrared emission, chiefly from dust within ...
A major difficulty was that, in this supposition, turbulent dissipation took place over the course of a single millennium, which did not give enough time for planets to form. The nebular hypothesis was first proposed in 1734 by Swedish scientist Emanuel Swedenborg [6] and later expanded upon by Prussian philosopher Immanuel Kant in 1755.
[5] [6] [7] Though the modern interpretation is different, the old term is still used. All planetary nebulae form at the end of the life of a star of intermediate mass, about 1-8 solar masses. It is expected that the Sun will form a planetary nebula at the end of its life cycle. [ 8 ]
Research is ongoing to understand this dark energy. Dark energy is now believed to be the single largest component of the universe, as it constitutes about 68.3% of the entire mass–energy of the physical universe. Dark energy is believed to act like a cosmological constant—a scalar field that exists throughout space. Unlike gravity, the ...
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. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion.
A dark nebula or absorption nebula is a type of interstellar cloud, particularly molecular clouds, that is so dense that it obscures the visible wavelengths of light from objects behind it, such as background stars and emission or reflection nebulae.