The English word “planet” comes from the ancient Greek word πλανήτης (planētēs), which literally means “wanderer.”

In ancient Greek astronomy, certain bright objects in the night sky (the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn) appeared to move against the background of the fixed stars, so the Greeks called them πλανῆτες ἀστέρες (planētes asteres), “wandering stars.” This expression comes from the verb πλανᾶσθαι (planasthai), “to wander,” emphasizing that these lights did not stay in fixed positions like the constellations.