Jupiter is the fifth planet out from the Sun and the largest by far.  It has more than twice the mass of all the other planets put together.  Its mass is 318 times greater than that of the Earth.  It is more than 778 million kilometres out from the Sun.  At its closest Jupiter is 628,780,000 km from the Earth.

It is the fourth brightest object in the sky after the Sun, the Moon and Venus.
Jupiter has 16 moons - Io, Europa, Ganymede and Callisto are the 4 largest and the ones about which most is known so far.  Callisto is almost as big as Mercury and Ganymede is considerably larger than Mercury.  The planet was first visited by Pioneer 10 in 1973 and then later by Pioneer 11, Voyager 1, Voyager 2 and Ulysees.  The spacecraft Galileo is currently in orbit around Jupiter and will sending back information for at least another 2 years.
Jupiter is a gas planet, and like the others, it does not have a solid surface.  What we see when we look at these planets are the tops of clouds high in their atmospheres. Jupiter's atmosphere is about 90% hydrogen and 10% helium.
Jupiter takes about 11.9 years to revolve once around the Sun and rotates about its own axis once every 9.8 hours.  The temperature on the planet surface ranges between  -125 and 17 degrees centigrade.

The picture below was taken by NASA's Voyager 1 spacecraft in 1979.  It shows both sides of Jupiter's closest moon, Io. Its colours are caused by the many volcanic eruptions on the surface and the constant lave flows.

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