planetesimal

[ plan-i-tes-uh-muhl ]

noun

1. one of the small celestial bodies that, according to one theory planetesimal hypothesis, were fused together to form the planets of the solar system.

adjective

1. of or relating to a planetesimal or planetesimals.

planetesimal

/ plăn′ĭ-tĕs′ə-məl /

1. Any of innumerable small bodies of accreted gas and dust thought to have orbited the Sun during the formation of the planets.
2. ◆ The theory that explains the formation of the solar system in terms of the aggregation of such bodies is known as the planetesimal hypothesis . According to this theory, first proposed in 1900, the planetesimals formed within a spiral disk of dust and gas surrounding a central nucleus. Their gravitational attraction eventually caused the planetesimals to coalesce into protoplanetary disks from which larger objects such as planets, asteroids, and satellites were formed, while the nucleus coalesced into the Sun.

Word History and Origins

Origin of planetesimal¹

First recorded in 1900–05; planet + (infinit)esimal

Example Sentences

These particles clump together, building up into bigger and bigger chunks called planetesimals.

From Science Daily

Over tens of millions of years, tiny pebbles of dust coalesced, like a snowball rolling larger and larger, to become kilometer-sized "planetesimals" -- the building blocks of Earth and the other inner planets.

From Science Daily

"If the mounds are indeed representative of the building blocks of ancient planetesimals like Arrokoth, then planetesimal formation models will need to explain the preferred size for these building blocks."

From Science Daily

While rocky planets like our Earth form from accretion and clash of dust, rocks and planetesimals.

From Space Scoop

"In this model, 'Oumuamua began as an icy planetesimal that was irradiated at low temperatures by cosmic rays during its interstellar journey, and experienced warming during its passage through the Solar System."

From Salon