Animation of the Juno spacecraft studying the polar aurorae of Jupiter. Juno is a NASA spacecraft designed to study the composition, gravity and magnetic field of Jupiter, the largest planet in the Solar System. Its magnetosphere is also the strongest of the planets, and its structure causes large, permanent aurorae (blue) around Jupiter's poles. Juno was launched on 5th August 2011 and will arrive at Jupiter on 4th July 2016. Once there, it will manoeuvre into a highly elliptical polar orbit, taking it as close as 4300 kilometres but then retreating away from the planet's damaging radiation belts. The mission is intended to last for 37 orbits, taking it to February 2018, before the probe is sent to plunge into the giant planet.