Starting to count from the Sun, the first four planets (Mercury, Venus, Earth, and Mars) are rocky: their surface is solid, like Earth's. In contrast, the remaining four (Jupiter, Saturn, Uranus, and Neptune) are made of gases. Our solar system has 8 planets, whose names come from Greek mythology, as the first observers were inspired by ancient myths. Particularly bright, Venus was associated with the goddess of beauty, while the red color of Mars reminded of the god of war. The deep blue of Neptune resembled his realm, the sea. As for Jupiter, the largest planet in the Solar System, it deserved the name of the king of the gods.