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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.


protoplanet British  
/ ˌprəʊtəʊˈplænɪt /

noun

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of protoplanet

First recorded in 1945–50; proto- + planet


Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

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

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

From New York Times ● Nov. 1, 2023

For decades, scientists have wondered whether Psyche could be the denuded metal core of a larger protoplanet.

From Science Magazine ● Oct. 13, 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

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