Jupiter is the largest of all the planets, with a diameter more than eleven times that of Earth. It has a greater mass than all the other planets combined. Because it has such a huge mass, it also exerts a huge gravitational force on everything around it. Some astronomers believe this force prevented the rocks in the asteroid belt from forming a tenth planet.

Because of the gravitational forces on Jupiter, we would be compressed into a puddle if we tried to walk around the planet! Its large size, plus the large amount of light reflected by its clouds, makes Jupiter very bright in the night sky.

Jupiter's most interesting features are its colored bands and the Great Red Spot. The Great Red Spot is believed to be a hurricane, larger than the size of two Earths. The storm is fed by constant high winds trigged by the enormous planet's very fast rotation -- only 9 hours and 50 minutes. Compare that to the much smaller Earth's 24-hour rotation! This hurricane existed hundreds of years ago, back when people first looked at Jupiter through telescopes. It still shows no sign of dying away.

Jupiter and its 16-or-so moons have been observed from close range by several space probes. (Pioneers 10 and 11, Voyagers 1 and 2, and Galileo). You might even be able to see four of these moons (Io, Europa, Ganymede and Callisto) through binoculars. And if you have a good telescope, you can see Jupiter's orbiting rings of rocks, a baby version of what Saturn has.

Although Jupiter is made of basically the same gases as the Sun, Jupiter is not a star. The reason for this is because the pressure is not great enough for the gases to have undergone nuclear fusion. The solar system was created about 5 million years ago. If Jupiter had grown only ten times greater in mass, then it would have formed another star, called a brown dwarf.

It's time for me to... BLAST OFF!

Rebok