Final answer:
Jovian planets vary in composition; Jupiter and Saturn are rich in hydrogen and helium with small rocky cores, while Uranus and Neptune have more compounds and large cores without metallic hydrogen layers.
Step-by-step explanation:
The interiors of the Jovian planets differ notably among Jupiter, Saturn, Uranus, and Neptune. While Jupiter and Saturn are primarily composed of hydrogen and helium, the cores make up only a small percentage of their total mass. Saturn resembles Jupiter in structure but has less metallic hydrogen due to its lower mass. On the other hand, Uranus and Neptune are mainly composed of compounds such as carbon, nitrogen, and oxygen, with most of their mass residing in their cores. This difference in composition indicates that they were unable to attract large quantities of hydrogen and helium while forming. Additionally, Saturn has a small volume of metallic hydrogen, whereas Uranus and Neptune do not have internal pressures high enough to form layers of metallic or liquid hydrogen. Instead, these planets have differentiated layers of hydrogen compounds near their cores.
Jupiter, being the most massive, is surrounded by an extensive mantle of liquid hydrogen and has a strong magnetic field resulting from its internal structure. In contrast, Uranus lacks an internal heat source, leading to a more featureless appearance. Neptune, while similar in size to Uranus, has a visible cloud structure and displays atmospheric activity.