Named after the Roman king of the gods, Jupiter is fitting of its name. With a mass of 1.90 x 1027 kg and a mean diameter of 139,822 km, Jupiter is easily the largest and most massive planet in the Solar System. To put this in perspective, it would take 11 Earths lined up next to each other to stretch from one side of Jupiter to the other and it would take 317 Earths to equal the mass of Jupiter.