any of the gears in an epicyclic train surrounding and engaging with the sun gear.
When To Capitalize “Earth”When it comes to writing, this common English word confuses many native speakers who aren’t sure whether to use Earth or earth. Why is this an issue? Earth can be either a proper noun or a common noun. In English, proper nouns (nouns which signify a particular person, place, or thing) are capitalized. Following this rule, when Earth is discussed as a specific planet or …
Origin of planet gear
First recorded in 1915–20
Also called planet wheel.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019