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Related to Planetesimals: Planetesimal theory


Any of innumerable small bodies thought to have orbited the sun during the formation of the planets.

plan′e·tes′i·mal adj.


(ˌplænɪˈtɛsɪməl) astronomy
(Astronomy) any of a number of small bodies formerly thought to have been drawn from the sun by the close passage of a star to the sun, eventually coalescing to form the planets
(Astronomy) of or relating to planetesimals


(ˌplæn ɪˈtɛs ə məl)
one of the small celestial bodies that, according to one theory, were fused to form the planets of the solar system.
[1900–05; planet + (infinit) esimal]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.planetesimal - one of many small solid celestial bodies thought to have existed at an early stage in the development of the solar system
celestial body, heavenly body - natural objects visible in the sky
References in periodicals archive ?
Their dynamical, radiative and thermodynamic properties critically define the environment for embedded solids: dust grains, pebbles and planetesimals.
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.
Terrestrial planet formation models indicate Earth went through a sequence of major growth phases: initially accretion of planetesimals, planetary embryos, over many tens of millions of years, then a giant impact by a large proto-planet that led to the formation of our Moon, followed by the late bombardment when giant asteroids several tens to hundreds of miles in size periodically hit ancient Earth, dwarfing the one that killed the dinosaurs only 65 million years ago.
The Earth is said to have gone through a series of major growth phases: the first and initial phase was an accumulation of over ten million years of planetesimals into a bigger body which became the planet; then comes the formation of the moon due to an impact with a large proto-planet; the third one is considered to be a periodic bombardment of asteroids, much bigger than that which led to the extinction of the dinosaurs.
Clumps of dust and ice aggregated into comets and asteroids, some of which collided together to form moon-sized objects or planetesimals, and some of those eventually merged to become planets.
Some dynamical aspects of the accretion of Uranus and Neptune--The exchange of orbital angular momentum with planetesimals.
Doing it right--that is, trying to capture the whole picture--includes starting ingredients called planetesimals.
A massive planet in an inclined orbit gravitationally attracts small bodies of rock and/or ice, called planetesimals, from the main disk, and moves them into an orbit aligned with that of the planet.
Also, the group said there are several dense areas with small celestial bodies, or planetesimals, in a dust disk within 7.
Asteroids are referred to as planetesimals -- tiny seeds that were denied the chance to accrete into anything larger.
The Interactions in Cosmic and Atmospheric Particle Systems (ICAPS) scientific program addresses planetary science and in particular it aims at understanding the formation of planetesimals or planet precursors by studying the mutual interactions of micron-sizeddust particles and their agglomeration in pre-planetary like conditions by means of the light scattering behaviour of these proto-planetary dust aggregates.
Planetesimals were extremely abundant in our primordial solar system--and some of them have survived long enough to tell the long-lost story of this vast population of primordial objects.