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Some elements of the original nebular theory are echoed in modern theories of planetary formation, but most elements have been superseded. According to the nebular theory, stars form in massive and dense clouds of molecular hydrogen—giant molecular clouds (GMC). These clouds are gravitationally unstable, and matter coalesces within them to ...
The nebular hypothesis says that the Solar System formed from the gravitational collapse of a fragment of a giant molecular cloud, [10] most likely at the edge of a Wolf-Rayet bubble. [11] The cloud was about 20 parsecs (65 light years) across, [10] while the fragments were roughly 1 parsec (three and a quarter light-years) across. [12]
Barnard's Loop; Barnard's Merope Nebula; Boomerang Nebula; Bubble Nebula, NGC 7635; Bubble Nebula in Barnard's Galaxy; California Nebula; Carina Nebula; Cave Nebula; Corona Australis Molecular Cloud
The Veil Nebula is a cloud of heated and ionized gas and dust in the constellation Cygnus. [ 4 ] It constitutes the visible portions of the Cygnus Loop , [ 5 ] a supernova remnant , many portions of which have acquired their own individual names and catalogue identifiers.
Impurities in the A-cloud formed Mars and the Moon (later captured by Earth), impurities in the B-cloud collapsed to form the outer planets, the C-cloud condensed into Mercury, Venus, Earth, the asteroid belt, moons of Jupiter, and Saturn's rings, while Pluto, Triton, the outer satellites of Saturn, the moons of Uranus, the Kuiper Belt, and the ...
The first true nebula, as distinct from a star cluster, was mentioned by the Muslim Persian astronomer Abd al-Rahman al-Sufi in his Book of Fixed Stars (964). [10] He noted "a little cloud" where the Andromeda Galaxy is located. [11]
The nebula nearest to the Sun where massive stars are being formed is the Orion Nebula, 1,300 light-years (1.2 × 10 16 km) away. [11] However, lower mass star formation is occurring about 400–450 light-years distant in the ρ Ophiuchi cloud complex .
The Oort cloud, one of the most successful theoretical models about the Solar System. Theoretical astronomy is the use of analytical and computational models based on principles from physics and chemistry to describe and explain astronomical objects and astronomical phenomena. Theorists in astronomy endeavor to create theoretical models and ...