Q: I love your blog, but I just want to point out an easily fixed typo in your posting about why English is a Germanic language. In the seventh paragraph of your answer, you refer to “the earth’s population.” The word “Earth” requires capitalization.
A: We’re glad you like the blog, but this isn’t a mistake. We properly used “earth” as a common noun.
As The Chicago Manual of Style (16th ed.) says, “In nontechnical contexts the word earth, in the sense of our planet, is usually lowercased when preceded by the or in such idioms as ‘down to earth’ or ‘move heaven or earth.’ ”
“When used as the proper name of our planet, especially in context with other planets,” the Chicago Manual adds, “it is capitalized and the is usually omitted.”
Other standard references agree.
The American Heritage Dictionary of the English Language (5th ed.), for example, says the word is often capitalized when it stands alone and refers to “the third planet from the sun.” Otherwise, it’s lowercased.
So unless you’re using it in a strictly astronomical sense (as in “the moons of Jupiter, Saturn, and Earth”), the word is lowercased. In fact, it’s sometimes lowercased even when used in reference to the planet.
As Merriam-Webster’s Dictionary of English Usage explains, “The names of planets other than our own are invariably capitalized, but earth is more often than not lowercased.”
The usage guide goes on to say that the name is more likely to be capitalized when it appears with the names of the other planets, as in “the moon, Mercury, Venus, Mars, and Earth.”
Another guide, Garner’s Modern American Usage (3rd ed.) says, “In reference to the planet we live on, earth is usually preceded by the and is not capitalized. The sun and the moon are treated the same way.”
Garner’s gives this example: “a full moon occurs when the sun and moon are on opposite sides of the earth.”
But “when Earth is referred to as a proper noun,” the usage guide says, “it is capitalized and usually stands alone.”
Garner’s gives this example from an article about the dwarf planet Quaoar: “It’s about one-tenth the size of Earth and orbits the sun every 288 years.”
The Old English word eorthe, which first showed up in in Beowulf around 725, could refer to the ground, the soil, or the earth, according to the Chambers Dictionary of Etymology. The modern spelling appeared in the last half of the 1500s.
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