(redirected from Planetesimals)
Also found in: Thesaurus, Encyclopedia.
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.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(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
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(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]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
According to the standard theory, the Earth is thought to have formed from the collision of small celestial bodies known as planetesimals. Since such bodies were poor in water, Earth's water must have been delivered either by a larger planetesimal or by a shower of smaller objects such as asteroids or comets.
Scientists think that the lobes of the Ultima Thule are "primordial planetary building blocks called planetesimals."
The Trappist-1 system is named after the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile, which discovered two of the planets in the system in February 2016.
In the so-called Nice Model, the giant planets that orbit our own Sun migrated inward and outward as they were forming, launching many planetesimals into interstellar space.
Both the asteroids and comets are relic planetesimals. The vast primordial population of ancient planetesimals served as the building blocks of the eight major planets of the sun's family.
In one, it occurs in stages, with small dust particles coalescing into "planetesimals" -- rock fragments ten to 100 kilometers in diameter -- that collide to form planetary embryos, and then planets, over a time scale of 50 to 100 million years.
In most models it is considered that the protoplanetary disk is formed by a distribution of continuous material, which as it rotates around the star, acquires dynamics (stable and / or turbulent), so that originates planets through a process of accretion of planetesimals.
The discovery was made using Europe's Transiting Planets and Planetesimals Small Telescope, or TRAPPIST, located at the La Silla Observatory in Chile.
The researchers used the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) to find the three Earth-like planets.
"It's the perfect recipe if you want to form planets or planetesimals," said Isella, of Rice University in Houston.
The current leading theory for planetary formation is the core-accretion model, in which a heavy element core is built by the accretion of planetesimals. As the core grows, its ability to accrete gas from the surrounding disk increases.