id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
en-wikipedia-org-4520		Nebular hypothesis - Wikipedia			.html	text/html	9783	1299	67	During the 20th century many theories addressed the issue, including the planetesimal theory of Thomas Chamberlin and Forest Moulton (1901), the tidal model of James Jeans (1917), the accretion model of Otto Schmidt (1944), the protoplanet theory of William McCrea (1960) and finally the capture theory of Michael Woolfson.[1] In 1978 Andrew Prentice resurrected the initial Laplacian ideas about planet formation and developed the modern Laplacian theory.[1] None of these attempts proved completely successful, and many of the proposed theories were descriptive. The star formation process naturally results in the appearance of accretion disks around young stellar objects.[14] At the age of about 1 million years, 100% of stars may have such disks.[15] This conclusion is supported by the discovery of the gaseous and dusty disks around protostars and T Tauri stars as well as by theoretical considerations.[16] Observations of these disks show that the dust grains inside them grow in size on short (thousand-year) time scales, producing 1 centimeter sized particles.[17]	./cache/en-wikipedia-org-4520.html	./txt/en-wikipedia-org-4520.txt