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Related to planetesimals: Planetesimal theory


(plan-ĕ-tess -ă-mălz) Bodies, ranging in size from less than a millimeter to many kilometers, that are thought to have formed the planets of the Solar System by a process of accretion.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the tiny solid particles that were the material for the formation of the planets according to the cosmogonical hypothesis advanced at the turn of the century by the American scientists F. Moulton and T. Chamberlin. The hypothesis attributed the formation of planetesimals to the cooling and condensation of matter ejected by the sun. This assumption, however, is not valid, since it is incapable of explaining the large distances and specific angular momenta of the planets. The term “planetesimal” is sometimes used in modern cosmogonical hypotheses and theories that consider the formation of the planets from solid particles.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Small planetesimals quickly gather mass by collecting other rocky material on their orbit around the Sun.
absorbing smaller planetesimals. Once the mass of these inner
See was critical of the planetesimal hypothesis, as it was known, and in 1909 attacked it in terms that drew a sharp response from Moulton, implying amongst other things that See, one of his former teachers at Chicago, had plagiarised his work; a charge he reiterated with biting sarcasm in a 1912 February critique 'Capture theory and capture practice', published in Popular Astronomy.
Second was the thought that Earth and Moon had formed separately from the same swirl of planetesimals. But the Earth and Moon should then have much the same chemical composition, and they don't.
In a study published in the scientific journal ( Nature Astronomy , researchers said this discovery could mean that planetesimals -- celestial bodies that could serve as building blocks for the formation of planets, moons and other larger bodies -- are the major population in the Kuiper Belt, also known as the Edgeworth-Kuiper Belt, at the moment.
According to these models, giant impacts mark the beginning of the end of a long process in which bits of rocky material gradually clump together, growing in size to form boulders, then planetesimals, and then planets.
As Jupiter moved inward, however, gravitational perturbations from the giant planet would have swept the inner planets (and smaller planetesimals and asteroids) into close-knit, overlapping orbits, setting off a series of collisions that smashed all the nascent planets into pieces.
Some dynamical aspects of the accretion of Uranus and Neptune--The exchange of orbital angular momentum with planetesimals. Icarus, 1984, v.
Four billion years ago Earth was intensely volcanic, having formed from the collision of several small "planetesimals" about 500 million years previously, the Daily Times reported.
Abstract: We describe the evolution of a protoplanetary disc from the initial accretion infall to FU Orionis outbursts to the formation of planetesimals. Protoplanetary discs are thought to contain a dead zone--a region without turbulence (or viscosity) that prevents free flow of material through the disc.
Doing it right--that is, trying to capture the whole picture--includes starting ingredients called planetesimals. These asteroid-sized chunks of material float within the protoplanetary disk, knocking into each other and occasionally forming bigger chunks.