Jupiter is probably the best place in the solar system to study how the magnetic fields of planets are generated. The Juno spacecraft will arrive at the Jovian system in July 2016, then circle the planet and collect data for more than one Earth year.
Cassini-Huygens Credit: NASA/JPL The Cassini-Huygens probe (a NASA-ESA-Italian Space Agency mission) is best known for its ongoing study of Saturn, which the spacecraft entered orbit around in 2004. But on its way to the ringed planet, Cassini passed by Jupiter in December 2000, three years after its launch in October 1997.
Pioneer 11A sister ship to its predecessor, Pioneer 11 was launched in April 1973. This craft became the second to fly through the asteroid belt and passed Jupiter in December 1974. Pioneer 11 went on to become the first spacecraft to encounter Saturn in July 1979. This probe captured detailed images of the Jovian Great Red Spot, as well as the planet's poles, and measured the mass of Jupiter's moon Callisto.
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune. Together, these four planets are sometimes referred to as the Jovian or outer planets.