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pro·to·plan·et | \ ˈprō-tō-ˌpla-nət 
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\Definition of protoplanet
: a hypothetical whirling gaseous mass within a giant cloud of gas and dust that rotates around a sun and is believed to give rise to a planet
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Other Words from protoplanet
protoplanetary \ ˌprō-tō-ˈpla-nə-ˌter-ē \ adjective
\ adjectiveExamples of protoplanet in a Sentence
Recent Examples on the Web Such an event would have seen Jupiter absorb the protoplanet, which would have been 10 times Earth’s mass, causing their two dense cores to combine and diffuse after only 10 hours, as seen in the simulation above.
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Paul Voosen, Science | AAAS, "Cataclysmic collision could explain Jupiter’s fuzzy core," 14 Aug. 2019 Scientific consensus about how the moon formed is that billions of years ago, a protoplanet crashed into Earth and the pieces of it revolved around the Earth to form the moon.
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Kristen Rogers, CNN, "The US proposed nuking the moon, and other surprising facts about Earth's celestial satellite," 22 Nov. 2019 Smaller objects, including Earth-sized protoplanets, would disintegrate in the atmosphere before reaching the core.
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John Timmer, Ars Technica, "Jupiter may have had a head-on collision with a massive protoplanet," 14 Aug. 2019 One possible explanation is a cataclysmic head-on collision some 4.5 billion years ago between a young Jupiter and one of the many large protoplanets that likely populated the early solar system, planetary scientists report today in Nature.
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Paul Voosen, Science | AAAS, "Cataclysmic collision could explain Jupiter’s fuzzy core," 14 Aug. 2019 Now, an international team of researchers is providing a possible explanation: Jupiter's core was shattered by a head-on collision with a massive protoplanet.
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John Timmer, Ars Technica, "Jupiter may have had a head-on collision with a massive protoplanet," 14 Aug. 2019 Because of the immense pull of Jupiter, most of the collisions ended up being head-on, sending the protoplanet directly to the core of Jupiter.
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John Timmer, Ars Technica, "Jupiter may have had a head-on collision with a massive protoplanet," 14 Aug. 2019 Earth’s moon formed nearly 4.5 billion years ago, in the aftermath of a cataclysmic collision between the proto-Earth and another protoplanet.
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Simon J. Lock, Scientific American, "When Earth and the Moon Were One," 2 July 2019 The moon probably formed from another protoplanet smashing into the young Earth, and a runaway planet has long been the suspected culprit behind the odd tilt of Uranus.
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John Wenz, Popular Mechanics, "We Might Finally Know What Smacked Uranus Sideways," 2 July 2018
See MoreThese example sentences are selected automatically from various online news sources to reflect current usage of the word 'protoplanet.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
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Time Traveler for protoplanet
The first known use of protoplanet was in 1949
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