How to Use protoplanet in a Sentence

protoplanet

noun
  • What was once believed to be the largest asteroid has now been revealed as a relict protoplanet that once had a since-frozen over ocean.
    — John Wenz, Discover Magazine, 3 July 2018
  • Beyond the question of how an angrite-spawning protoplanet could have arisen so early on, the details of its demise are unknown.
    — Jenna Ahart, Scientific American, 9 June 2026
  • Ceres is a protoplanet—a body that seems to be slowly developing into a planet.
    — Erin Blakemore, Smithsonian, 17 Feb. 2017
  • It is thought to be a fragment of an igneous crust of a primitive protoplanet from the early solar system.
    — Eva Botkin-Kowacki, Popular Science, 22 Jan. 2023
  • But scientists have lacked smoking-gun evidence like a crater or pieces of the protoplanet, named Theia.
    — Kenneth Chang, New York Times, 1 Nov. 2023
  • The vast majority of both protoplanets wound up forming the Earth, while a large amount of debris was kicked up into space.
    — Big Think, 26 Nov. 2025
  • This artist's concept shows the heavy metal asteroid Psyche, which is thought the be a piece of an ancient protoplanet's core.
    — Jake Parks, Discover Magazine, 5 Apr. 2019
  • That's because astronomers think swarms of protoplanets — balls of gas, dust, and rock about the size of Mercury or Mars — once swirled around our young sun.
    — National Geographic, 17 Apr. 2018
  • The diamonds themselves may have been larger until the protoplanet was destroyed.
    — John Wenz, Popular Mechanics, 17 Apr. 2018
  • Scientists think the all-metal asteroid Psyche was once the core of a protoplanet.
    — Nathaniel Scharping, Discover Magazine, 12 June 2017
  • The new measurements are significant as this is the first time water has been detected in a region where two or more protoplanets are known to exist.
    — Jack Birle, Washington Examiner, 25 July 2023
  • Fortunately, the study of protoplanets is just getting started.
    — Jay Bennett, Popular Mechanics, 13 June 2018
  • And the authors think there are more protoplanets to find around WISPIT 2.
    — Joseph Howlett, Scientific American, 24 Mar. 2026
  • The diamond pieces inside the meteorite hold a compelling record of these protoplanets and their collisions, according to the study.
    — Doris Elin Salazar, Scientific American, 18 Apr. 2018
  • The early solar system was little more than a faint protosun surrounded by gas, dust and the odd protoplanet, as in this illustration.
    — Douglas Fox, Discover Magazine, 16 May 2017
  • Come find out the incredible science behind planet formation, and meet our first-ever proto-protoplanet in the process!
    — Big Think, 11 Apr. 2026
  • And when a protoplanet gets massive enough, gravity forces it into a spherical shape, finally cementing its status as a true planet.
    — Jake Parks, Discover Magazine, 11 July 2018
  • 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.
    — Kristen Rogers, CNN, 22 Nov. 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.
    — John Timmer, Ars Technica, 14 Aug. 2019
  • The cloud's relatively close proximity to Earth lends it to further study by astronomers wanting to learn more about how stars, and the protoplanets that circle them, form.
    — Jeffrey Kluger, Time, 18 Dec. 2025
  • The protoplanet in question may have originated in the outer solar system and migrated inward to the inner solar system.
    — John Wenz, Popular Mechanics, 17 Apr. 2018
  • Scientists think that the moon formed when a Mars-size protoplanet called Theia slammed into Earth, forming debris that coalesced into the moon.
    — Keith Cooper, Space.com, 13 Oct. 2025
  • In its violent early years, Earth was a molten hellscape that ejected the moon after a fiery collision with another protoplanet, scientists now suspect.
    — Bryn Nelson, CNN, 22 Jan. 2023
  • Cataclysmic collisions with protoplanets, asteroids and comets are thought to be common during a planet’s formation and for the next tens to hundreds of millions of years thereafter.
    — Conor Feehly, Scientific American, 4 Mar. 2025
  • The combination of these unique features allowed scientists to observe the transiting protoplanet.
    — Julia Jacobo, ABC News, 20 Nov. 2024
  • The discoveries, and the new method used to make them, are a thrilling advancement of exoplanet sciences to include protoplanets still in the process of formation, which were previously hidden from view.
    — Jay Bennett, Popular Mechanics, 13 June 2018
  • Scientists have found the first hard evidence of a large and ancient protoplanet embedded in extraterrestrial diamonds that fell to Earth about 10 years ago.
    — Deborah Netburn, latimes.com, 17 Apr. 2018
  • Smaller objects, including Earth-sized protoplanets, would disintegrate in the atmosphere before reaching the core.
    — John Timmer, Ars Technica, 14 Aug. 2019
  • In fact, some of the potential culprits could have been so large as to essentially be a still-developing protoplanet, according to NASA.
    — Eric Lagatta, USA Today, 4 Sep. 2025
  • One is that the isotopic ratios of sulfur are a legacy not of Earth, but of the chemical composition of Theia, and that more of the moon is made from debris originating from this ancient protoplanet than had been thought.
    — Keith Cooper, Space.com, 13 Oct. 2025

Some of these examples are programmatically compiled from various online sources to illustrate current usage of the word 'protoplanet.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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