Jupiter is the biggest planet in the solar system. Jupiter, mainly made of hydrogen and helium, has a mass of 1.8986×10²⁷ kg, which is 317 times Earth's mass. If you add the mass of all the other planets in the solar system, and double it, the figure is still less than the mass of Jupiter. That is all heavy Jupiter is! The diameter at equator of Jupiter is 142,984 km (88,984 miles) , which is over 11 times of Earth's diameter. Although Jupiter is shrinking down, the rate is very slow at 2cm per year. So it will remain as the biggest star in the solar system for many many years.

It takes Jupiter 9.93 hours to spin around its axis, which is so rapid that makes the clouds in its atmosphere from bands. Those bands are called belts and zones.
Jupiter has 63 moons, among which, Ganymede, Callisto, Io, Europa are the largest moons. Those four mons were discovered by Galileo Galilei, an Italian astronomer, in 1610.