Jupiter outdoes all other planets. If you tossed all the other planets inside Jupiter, you wouldn’t have filled it even halfway. Jupiter also rotates faster than other planets, so a day on Jupiter is only ten hours long. Scientists also predict that Jupiter has more moons than any other planet—67 of them. Jupiter is the star of all the planets, and in fact, it has a lot in common with actual stars since it is made of hydrogen and helium gas. Unfortunately for Jupiter, it would need to be quite a bit bigger—about 75 times more massive—before it could be a real star.