The Planet Jupiter, number 5 in a set of 9 prints featuring the planets of our Solar System. Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. The planet was known by astronomers of ancient times and was associated with the mythology and religious beliefs of many cultures. The Romans named the planet after the Roman god Jupiter. Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune. Together, these four planets are sometimes referred to as the Jovian or outer planets. The Great Red Spot is a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Jupiter has 64 moons.