Final answer:
The Jovian planets are primarily made up of hydrogen and helium with cores of rock and ice. The cores contain elements like iron, silicon, and oxygen for 'rock', as well as carbon, nitrogen, and oxygen for 'ice'. These cores are subjected to intense pressures and temperatures, with varying proportions of hydrogen and helium surrounding them.
Step-by-step explanation:
The giant planets, also known as the Jovian planets, primarily consist of hydrogen and helium and have interior structures that are quite complex. Each of these planets possesses a core composed of heavier materials, such as rock and ice, at very high pressures. Unlike anything we might find on Earth, these cores are made up of iron, silicon, and oxygen in the case of 'rock,' and carbon, nitrogen, and oxygen in combination with hydrogen for 'ice.' Surrounding the cores are layers of hydrogen and helium, with the proportions varying across the different giant planets. Jupiter and Saturn, for instance, have cores that make up only a small percentage of their total mass, while a significant portion of the mass of Uranus and Neptune is found in these dense cores, suggesting that they captured less hydrogen and helium during their formation.
It is important to note that while the atmospheric compositions can be directly measured, much of our knowledge about the interior compositions comes from calculations and the analysis of gravitational fields. The cores of these giant planets likely do not assume familiar forms due to the extreme pressures and temperatures present at those depths. Because of their massive size, the interior pressures and temperatures are extremely high, preventing hydrogen and helium from remaining in their gas phase, potentially creating forms like metallic hydrogen.