protoplanet

[proh-toh-plan-it]

noun

Astronomy.

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

protoplanet

/ ˌprəʊtəʊˈplænɪt /

noun

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

Word History and Origins

Origin of protoplanet¹

First recorded in 1945–50; proto- + planet

Example Sentences

About 4.5 billion years ago, a dramatic event transformed the young Earth when a large protoplanet known as Theia struck our planet.

Read more on Science Daily

The chaos would have influenced the size, location, and composition of the rocky planets, and many researchers believe it could also explain why a Mars-size protoplanet crashed into Earth around this time, creating the Moon.

Read more on Science Magazine

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

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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.

Read more on National Geographic

The most popular theory says that about 4.5 billion years ago, a Mars-size protoplanet slammed into Earth.

Read more on New York Times