What some people might not know is that Jupiter was one of the first planets to form in our Solar System. Thus, inside Jupiter there is very important information about the first moments and history of the whole planetary region. For example its chemical composition would be a good indication of what the cloud from which the Solar System was born was like.
The important thing is that information is kept there for millions of years and one needs only to get to it, read it and interpret it. Jupiter is mainly a gas planet. It is not like Earth, a rocky planet which had geological processes affecting its shape and composition. In addition, Jupiter is the largest planet in our planetary system and therefore had great influence on smaller planets, asteroids and comets, as it determined the orbits of all these celestial objects. Some of them, due to the influence of Jupiter, even fell to Earth. It is believed that the water we have on Earth today actually arrived in one of these objects. If we understand Jupiter better, we will be able to better understand the history of Earth as well.
This year the Juno mission arrived or got close to the atmosphere of Jupiter. There was of course a lot of tension surrounding the complex maneuvers because the space probe sent to investigate Jupiter could have been burnt entering the atmosphere or destroyed by asteroids or similar objects, plus Jupiter is surrounded by rings made of particles whose composition is unknown and that radiation. So there was always the risk that this stardust might have ended damaging the probe. The mission was successful, though, as Juno was the first probe designed to operate in the heart of the radiation belts of the giant planet: the result was made even more extrardinary by the fact that Juno was controlled through computer from Earth: now scientists just need to start interpreting the data it will send back from up there.