The planets in the solar system are named after the Roman Gods. Mercury is the smallest and closest planet to the Sun. It is named after the Roman God Mercury, who was the fast-flying messenger of the Gods, because it moves very fast. Venus is the second planet from the Sun. It is named after the Roman Goddess of love and beauty. Mars is the fourth planet from the Sun and the second smallest planet. It is named after the Roman God of war. The fifth planet from the Sun is Jupiter. It is also the largest planet. The Romans named the planet after the Roman God of thunder and lightning. Saturn is the sixth planet from the Sun and the second largest planet. It is named after the Roman God of agriculture. Neptune is the eighth planet from the Sun in the Solar System. It is named after the Roman God of the sea.