inner planet


Definition of inner planet 

: any of the planets Mercury, Venus, Earth, and Mars whose orbits are within the asteroid belt

Examples of inner planet in a Sentence

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BepiColombo will also be using the inner planets for help. Loren Grush, The Verge, "Two spacecraft are embarking on a seven-year journey to decode Mercury’s mysteries," 19 Oct. 2018 Mercury remains our solar system's least studied inner planet, with only NASA's Mariner 10 and MESSENGER probes getting prior looks. David Grossman, Popular Mechanics, "The BepiColombo Probe Is About to Being a 7-Year Mission to Mercury," 19 Oct. 2018 Instead, all planetary systems fortunate enough to host a gas giant in their outskirts should automatically have water-rich material falling on their rocky inner planets. Nola Taylor Redd, Smithsonian, "How Jupiter May Have Gifted Early Earth With Water," 20 June 2018 Accordingly, unlike the inner planets that move quickly and govern daily activities, Uranus defines major periods of life with its prolonged revolutions. Aliza Kelly Faragher, Allure, "What May's Gemini Horoscope Means for You," 26 Apr. 2018 This conflict between the outer and inner planets is a defining point for a majority of the novel series: the books look closely at how massive imbalances of power and wealth can play out in new social and technological contexts. Andrew Liptak, The Verge, "Now is the perfect time to start watching The Expanse," 24 May 2018 As our solar system formed, the early sun blasted the inner planets with radiation and high-speed plasma, which drove off most of the gases (hydrogen, water vapor and CO2). Scott Denning, Washington Post, "May the 4th be with Earth, a perfect planet that’s not too Hoth or Tatooine," 4 May 2018 How the light from the distant star flickers and mutates over time will provide a wealth of information about any inner planets. Daniel Clery, Science | AAAS, "What is Alpha Centauri hiding? Searches for Earth-like planets ramp up around our nearest stellar neighbor," 11 Apr. 2018 Planet Nine’s gravitational influence could even serve as a solution to the long-standing mystery of why the sun’s axis of spin is tilted six degrees askew to the orbits of the inner planets. Lee Billings, Scientific American, "Looking for Planet Nine, Astronomers Gaze into the Abyss," 22 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'inner planet.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of inner planet

1951, in the meaning defined above

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Last Updated

16 Nov 2018

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The first known use of inner planet was in 1951

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