Mercury, Venus, Mars, Jupiter and Saturn are the five planets that are visible without a telescope. These five planets were known to ancient astronomers long before the invention of telescopes. Some experts also include the Earth on the list of planets you can see with the naked eye.
Ancient astronomers considered these five planets, along with the moon and the sun, to be the seven special celestial objects. This gave rise to the notion of seven heavens in many ancient religions. Ancient astronomers used the movements of the planets to track the seasons, decide when to plant crops and to predict the future.