Jupiter

Jupiter is the fifth planet from the Sun. It is the biggest planet in our whole solar system. Jupiter is so huge that it weighs almost as much as all the other planets put together. The planet is about eleven times wider than Earth.

Jupiter takes twelve years to go around the Sun one time. You can see Jupiter in the night sky without a telescope. Only the Moon and Venus look brighter than Jupiter. People have looked at Jupiter in the sky for thousands of years. The Romans named it after their most important god.

Jupiter formed before all the other planets. When it moved closer to the Sun long ago, it changed how the other planets formed. The air around Jupiter is mostly hydrogen and helium gas. These are the same gases that make up the Sun. Jupiter also has some water, ammonia, and other things in its air.

Jupiter spins around very fast. It turns all the way around in just ten hours. Because it spins so fast, the planet looks a little squashed at the top and bottom. Inside Jupiter, it is very hot and heavy. The planet makes its own heat from inside. This heat comes from the planet slowly squeezing itself smaller and smaller. Jupiter has a super strong magnetic field that is the second biggest thing in our solar system.

At least one hundred fifteen moons travel around Jupiter. Four of these moons are really big and easy to see with binoculars. The biggest moon is called Ganymede, and it is even bigger than the planet Mercury. Jupiter also has rings around it like Saturn does. The rings are made mostly of dust and are very faint. Space robots have visited Jupiter nine times since 1973 to study it up close.