This shows the South Polar region of Jupiter with the Great Red Spot clearly visible. Pioneer 11, launched on 6th April 1973, took many such pictures of Jupiter and its moons, Callisto, Ganymede and Europa (but not Io), before travelling on to rendezvous with Saturn in September 1979. Pioneer 11 has now left the solar system. The largest planet in the solar system, Jupiter is a type of planet known as a gas giant, with an atmosphere composed mainly of hydrogen and helium. The atmosphere contains a number of large storms, of which the Great Red Spot is the most famous. It is larger than the Earth and has been in existence for at least 300 years.
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