planetesimal

noun

plan·​e·​tes·​i·​mal ˌpla-nə-ˈte-sə-məl How to pronounce planetesimal (audio)
-zə-məl
: any of numerous small celestial bodies that may have existed at an early stage of the development of the solar system

Examples of planetesimal in a Sentence

Recent Examples on the Web The gravity of a passing star can eject smaller bodies, known as planetesimals, from the outer reaches of a system, according to a recent study led by Pfalzner. Theo Nicitopoulos, Discover Magazine, 17 Feb. 2024 Instead, it may have been ejected during the death throes of its star: Pulses of gas from a dying star could push planets and planetesimals outward, destabilizing their orbits enough to send some of them flying into interstellar space. Theo Nicitopoulos, Discover Magazine, 17 Feb. 2024 If iron meteorites are core fragments of planetesimals smashed apart by impacts, then planetesimals must have actually formed, melted and created iron cores within that tiny period. Linda T. Elkins-Tanton, Scientific American, 1 Dec. 2016 Scientists believe the asteroid, known as 16 Psyche, may be remnant core material of a small planetesimal that was broken up in the distant past. William Harwood, CBS News, 13 Oct. 2023 The authors suggest 'Oumuamua was born in its home planetary system as a water-rich planetesimal, resembling a comet. Conor Feehly, Discover Magazine, 20 Apr. 2023 The moon had a cataclysmic origin—the result of a collision between Earth and a passing planetesimal 4.5 billion years ago. Jeffrey Kluger, Time, 1 Aug. 2023 Typical planetesimals aren’t dissimilar to comets that form at the edge of the solar system, but observations quickly showed that something wasn’t quite right. Conor Feehly, Discover Magazine, 20 Apr. 2023 This merging occurred even as planetesimals were forming from dust. Linda T. Elkins-Tanton, Scientific American, 1 Dec. 2016

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'planetesimal.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

planet + -esimal (as in infinitesimal)

First Known Use

1903, in the meaning defined above

Time Traveler
The first known use of planetesimal was in 1903

Dictionary Entries Near planetesimal

Cite this Entry

“Planetesimal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/planetesimal. Accessed 29 May. 2024.

Kids Definition

planetesimal

noun
plan·​e·​tes·​i·​mal ˌplan-ə-ˈtes-ə-məl How to pronounce planetesimal (audio)
-tez-
: one of numerous small solid heavenly bodies which may have existed at an early stage of the development of the solar system and from which the planets may have been formed

More from Merriam-Webster on planetesimal

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!