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Planet goes back to ancient Greek planēt- (literally, "wanderer"), which is derived from planasthai, a Greek verb which means "to wander." The word was originally applied to any of seven visible celestial bodies which appeared to move independently of the fixed stars—the sun, the moon, Mercury, Venus, Mars, Jupiter, and Saturn. In line with astronomical discovery and advancement, planet began to be used specifically of the rocky or gaseous bodies that orbit around the sun—a definition which excluded the moon and the sun but included the Earth and, as they were discovered, Uranus, Neptune, and Pluto. In 2006, the International Astronomical Union developed a narrower definition of planet, effectively demoting Pluto to the status of a "dwarf planet," a celestial body that is spherical and orbits the sun but is not large enough to disturb other objects from its orbit.
Examples of planet in a Sentence
April Ehrlich, ProPublica, 12 Nov. 2024
Failure would be deeply embarrassing and, more pressingly, dangerous for the planet.
—Zoë Schlanger, The Atlantic, 5 Nov. 2024
Astronomers have been searching the Kuiper Belt for a hidden planet for more than a decade.
—Jacopo Prisco, CNN, 5 Nov. 2024
The journey ahead promises not only to push the limits of exploration but to redefine our relationship with the universe and, most importantly, to better protect our planet.
—Shelli Brunswick, Forbes, 5 Nov. 2024
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Cite this Entry
“Planet.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/planet. Accessed 22 Nov. 2024.
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planet
noun
Middle English planete "planet," from early French planet (same meaning), from Latin planeta (same meaning), from Greek planēt-, planēs "planet," literally, "wanderer"
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