Juno and Jupiter's aurorae. Illustration of NASA's Juno spacecraft over Jupiter's pole, studying the planet's aurorae. Juno was launched in 2011 on a five-year flight to Jupiter. Unlike previous Jupiter missions, it uses solar panels. Previous Jupiter missions were powered by generators fuelled by radioactive decay of nuclear isotopes. After arriving in July 2016, Juno will orbit Jupiter 32 times over the next year, gathering information about the planet's atmosphere, magnetic field and gravitational field. Jupiter, with a diameter of 142, 984 kilometres, is the largest of the planets.