The word "planet" comes from the ancient Greek word "planētēs," which means "wanderer." This term was used by the Greeks to describe celestial bodies that appeared to move across the sky in relation to the fixed stars. The word is derived from the Greek verb "planasthai," meaning "to wander." Originally, the term referred to the "wandering stars" visible to the naked eye, including the Sun and Moon, which were considered planets in ancient times. The modern scientific meaning of "planet" as a world orbiting a star emerged in the 1630s in English.