Mars
Americannoun
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the ancient Roman god of war and agriculture, identified with the Greek god Ares.
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Astronomy. the planet fourth in order from the sun, having a diameter of 4,222 miles (6,794 km), a mean distance from the sun of 141.6 million miles (227.9 million km), a period of revolution of 686.95 days, and two moons.
adjective
noun
noun
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Also called: the Red Planet. the fourth planet from the sun, having a reddish-orange surface with numerous dark patches and two white polar caps. It has a thin atmosphere, mainly carbon dioxide, and low surface temperatures. Spacecraft encounters have revealed a history of volcanic activity and running surface water. The planet has two tiny satellites, Phobos and Deimos. Mean distance from sun: 228 million km; period of revolution around sun: 686.98 days; period of axial rotation: 24.6225 hours; diameter and mass: 53.2 and 10.7 per cent that of earth respectively
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the alchemical name for iron
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The fourth planet from the Sun and the second smallest in the solar system, with a diameter about half that of Earth. Mars is the last of the terrestrial or inner planets and has notable similarities to Earth, including polar ice caps and a tilted axis that gives it seasons. However, it is significantly less dense than Earth and has no magnetic field, suggesting that it lacks a metallic core, and its atmosphere, made up mostly of carbon dioxide, is much thinner than Earth's. Mars has no surface water apart from a layer of permanent ice that underlies the seasonally changing caps of frozen carbon dioxide at its poles; there is, however, clear evidence of earlier water flows in the form of channels, outwashes, and canyons. Other surface features include numerous craters, especially in the southern hemisphere, along with very large volcanoes and extensive windblown dunes. Mar's reddish color is due to the abundance of hematite in its surface rocks. Its two small, irregular moons, Phobos and Deimos, may be asteroids captured earlier by gravitational attraction.
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See Table at solar system
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The month of March is named after Mars.
The fourth planet from the sun (the Earth is third) is named Mars, possibly because its red color is reminiscent of blood.
Smaller than the Earth, Mars has polar ice caps and a surface that includes red sands.
Mars has been, and remains, the focus of space research by NASA. Voyages to Mars, including multiple landings, are scheduled through the first decade of the twenty-first century.
The Viking space mission, which placed landers on the surface of Mars, did not discover any signs of life.
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Example Sentences
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That valuation is largely based on faith that Musk can deliver on his ambitions to vastly expand his Starlink satellite business, put data centers into space using SpaceX rockets, as well as begin colonizing Mars.
From Barron's • Jun. 5, 2026
Musk plans to use the extra money he is raising to expand SpaceX's current activities but also to fund new future ventures: mining asteroids, colonising Mars and putting AI data centres in space.
From BBC • Jun. 4, 2026
The SpaceX presentation highlights Musk’s ambitions, from traveling to Mars to putting data centers in space.
From MarketWatch • Jun. 4, 2026
Investors’ acceptance of SpaceX’s mammoth valuation will likely hinge on whether they believe Musk can deliver on his ambitious ideas, which include colonizing Mars and launching data centers into space.
From The Wall Street Journal • Jun. 3, 2026
“It would help us learn a lot more about the climate and atmosphere of Mars if we could get that data from Courage.”
From "A Rover's Story" by Jasmine Warga
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
