Jupiter (Courtesy to Microsoft Encarta for this photograph.)

Among the Solar System, Jupiter is the first Outer Planet toward the Sun and is the largest planet of the whole Solar System. It not only is large but also has many interesting tidbits about it. Jupiter's diameter is the length of eleven Earths. Its volume could hold more than one thousand Earths, and it has more material than all of the other planets combined. Also Jupiter has a very large storm of gases called the Great Red Spot. This Great Red Spot, first spotted in 1655, varies in size, but when it is at its largest, it is as large as three Earths. Other than Saturn, Jupiter has the most moons with sixteen moons altogether. Its four largest moons are Io, Europa, Ganymede, and Callisto. These four moons are called the Galilean moons, after the Italian astronomer Galileo.

Scientists have always known that Jupiter has a magnetic field, because Jupiter gives of radio waves. Later space probes detected just how large and powerful it is. Pioneer space probes detected that the magnetic field was ten times stronger than Earths, and Voyager space probes found that the magnetic field was larger than the Sun. This magnetic field traps particles from the Sun and causes large amounts of radiation around the planet.

Space probes with added support found out that Jupiter has rings. They are very faint but there are photographs of them. Their outer edge is about 34,000 miles above Jupiter's atmosphere and it is about eighteen miles thick. They were first detected by the flybys of Voyager 1 and Voyager 2. Before those flybys, astronomer's had no idea that Jupiter had rings. Scientists now think that the rings are caused by the eruptions of volcanoes on Jupiter's moon Io.

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