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Explainer: What is a planet? | Science News for Students
The ancient Greeks first coined the name “planet.” The word means “wandering star,” according to David Weintraub. He’s an astronomer at Vanderbilt University in Nashville, Tenn. Aristotle, the Greek natural philosopher who lived over 2,000 years ago, identified seven “planets” in the sky. These are the objects that today we call the sun, moon, Mercury, …