Our solar system is made up of eight planets, which can be separated into two categories. Those residing within the asteroid belt called the "Inner Solar System", i.e. Mercury, Venus, Earth and Mars designate the terrestrial or rocky planets while those orbiting beyond the asteroid belt, Jupiter, Saturn, Uranus and Neptune classified as the "Jovian Planets" include the "External Solar System". The term Jovian comes from Jupiter, which describes the remaining three planets as Jupiter-like. Unlike the inner terrestrial planets, Jovian worlds are composed of gases, mainly hydrogen and helium, and therefore do not have a solid surface. The four are the largest planets in our solar system if not in mass, then in diameter with Jupiter having the status of giant among giants acquiring more than double the mass of all the other planets in the solar system put together. Using just Earth as a comparison, Jupiter's mass is more than three hundred times greater. These planets became so massive because they were able to incorporate huge amounts of volatile substances, gases, when they formed; with some hypotheses suggesting that they may also have been the first planets in our solar system to evolve. Therefore, to explore the nature and formation of these categories of planets we must go back to the primordial solar nebula to ascertain the available materials and the environmental conditions necessary for their possible evolution. From many observations and studies it now appears certain that stars comparable to our Sun were formed at the center of cold and dense molecular clouds. Consisting mainly of hydrogen, helium with smaller quantities of heavier gases and dust; the residue of minerals and elements left by explosions from...... middle of paper ...... intrinsic nature of Jupiter's interior and structure. It will be able to look beneath observable cloud layers for the first time and collect data on atmospheric composition, temperature and movement at unprecedented depths. Juno will also sample and monitor the planet's enormous magnetosphere with particular attention to its relationship to the large level of metallic hydrogen beneath its surface. More importantly for theories about how the Jovian atmosphere planets formed will attempt to clarify whether or not Jupiter has a solid core and if so its composition. Otherwise it could profoundly upset theories about the role of planetesimals in planet formation and possibly infer that Jovian planets evolved instead from a gravitational collapse in unstable regions of the protoplanetary disk or an entirely new explanation for their formation...