protoplanet

American  

[proh-toh-plan-it] / ˈproʊ toʊˌplæn ɪt /

noun

Astronomy.

1. the collection of matter, in the process of condensation, from which a planet is formed.

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protoplanet British  

/ ˌprəʊtəʊˈplænɪt /

noun

1. a planet in its early stages of evolution by the process of accretion

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Etymology

Origin of protoplanet

First recorded in 1945–50; proto- + planet

Example Sentences

A giant collision between the young Earth and a smaller protoplanet has long been the prevailing theory for the Moon’s formation.

From Scientific American • Nov. 2, 2023

The collision was so powerful, it broke apart that impacting protoplanet, nicknamed Theia, and sent huge amounts of material into orbit around Earth—material that eventually coalesced into the moon.

From National Geographic • Nov. 1, 2023

"We think the Earth-Moon system formed following a giant impact between early Earth and another protoplanet," said Rufu, a Sagan Fellow who is the second author of a Science Advances paper.

From Science Daily • Sep. 18, 2023

These rocks helped show, for example, that the moon probably formed after an extremely violent collision between baby Earth and another protoplanet.

From New York Times • Dec. 14, 2022

If a protoplanet gets to several Earth masses, it can grab a thick envelope of gas and become a gas giant like Jupiter or Saturn.

From Science Magazine • Apr. 3, 2022