What does the word "planet" mean?
The word is typically traced back to the ancient Greeks, who believed the Earth was stationary at the center of the universe while objects in the sky revolved around it. The Greek term asters planetai mean "wandering stars" and described the tiny lights that moved across the sky more dramatically than stars when compared over weeks and months. These wandering stars, back then, amounted to Mercury, Venus, Mars, Jupiter and Saturn.