Definition of planetesimal
: any of numerous small celestial bodies that may have existed at an early stage of the development of the solar system
Recent Examples of planetesimal from the Web
Dust grains grew into pebbles, and pebbles became world-building planetesimals.
These are thought to be fragments of the cores of planetesimals that formed early in the Solar System's history.
The planets formed in a disk of gas and dust surrounding the sun where dust collided together to make pebbles, and then pebbles came together to make planetesimals hundreds of kilometers wide.
The largest of these planetesimals grow faster than the ones around them and swallow their neighbors to grow into proto-planets.
Dwarf planets have been defined by the International Astronomical Union since 2006 as celestial bodies that are roundish like their larger cousins in the solar system, but which haven’t gobbled up all the other planetesimals near themselves.
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Origin and Etymology of planetesimal
planet + -esimal (as in infinitesimal)
First Known Use: 1903See Words from the same year
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