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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 ]
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.
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.
The three forces of the Standard Model are still unified (assuming that nature is described by a Grand Unified Theory, gravity not included). Inflationary epoch Electroweak epoch < 10 −32 s: 10 28 K ~ 10 22 K (10 15 ~ 10 9 GeV) Cosmic inflation expands space by a factor of the order of 10 26 over a time of the order of 10 −36 to 10 −32 ...
His treatise De Luce is the first attempt to describe the heavens and Earth using a single set of physical laws. [51] 14th century – Jewish astronomer Levi ben Gershon (Gersonides) estimates the distance to the outermost orb of the fixed stars to be no less than 159,651,513,380,944 Earth radii, or about 100,000 light-years in modern units. [52]
The first planetary nebula discovered (though not yet termed as such) was the Dumbbell Nebula in the constellation of Vulpecula.It was observed by Charles Messier on July 12, 1764 and listed as M27 in his catalogue of nebulous objects. [10]
The W51 nebula in Aquila - one of the largest star factories in the Milky Way (August 25, 2020). Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or "star-forming regions", collapse and form stars. [1]