Jupiter is the fifth planet from the sun and the largest planet in the solar system. Jupiter's average distance from the sun is 483.6 million miles. Jupiter's gravitational pull is 318 times stronger than here on Earth. Jupiter's year is almost 12 Earth years long, but its day is only 10 hours long, which means it has the shortest rotational peroid (day) out of all the planets. Jupiter was named after the leader of the Roman gods.

Jupiter's Interior and Atmosphere

Jupiter is made up of helium and hydrogen, like stars. Jupiter isn't round because it rotates very fast, that makes its side bulge out and the poles flatten. Jupiter's mantle is probably made of hydrogen in a form of a metallic liquid, which is probably the cause of the strong gravitational pull. Jupiter has very colorful clouds, which scientists believe are caused by the motions of the clouds itself. The warm gases coming up to the surface are lighter colors than the cooler gases that are sinking.

The Great Red Spot

The Great Red Spot is what scientists think is a big storm on Jupiter. It has been seen through telescopes for nearly 300 years but no one recorded it like Pioneer 10. Nobody knows how long it has been there. Scientists believe it is on Jupiter's southern hemisphere and is about as wide as two Earths side by side. Lots of other storms have been spotted on Jupiter but none as big as the Great Red Spot.

Jupiter's Rings

Jupiter has three rings, together they are a few miles thick and 5000 miles wide. The largest ring is made of chunks of material. The other two are made of very tiny parts of ice and rock.

Jupiter's Moons

Jupiter has 16 known moons, the largest four are known as the Galilean satellites because they were discovered in 1610 by Galileo.

Callisto, the outermost of them seems to be ice covered with some dark material, probably dust and debris. Ganymede is the largest satellite in the solar system, it is even larger than Mercury and Pluto. Both of these moons are heavily cratered. Europa, the smallest of the Galilean satellites is very different from Ganymede and Callisto. It's surface if covered with ice that is cracked. Scientists believe that there may be water beneath the sheet of ice. Io, the innermost of the four satellites, has a surface with red, yellow, and dark brown shades. Io is made of sulfur and is the most volcanically active world in our solar system. Io is just slightly larger than our moon.