Final answer:
Jupiter generates internal heat primarily through contraction, converting gravitational potential energy to thermal energy, a process that is enhanced by its large mass.
Step-by-step explanation:
The most likely method by which Jupiter generates its internal heat is by contracting, changing gravitational potential energy into thermal energy. During Jupiter's formation, the collapse of material onto its core produced significant heat, and some of this primordial heat remains today. Moreover, because Jupiter has such a large mass, even a small amount of contraction can release immense amounts of heat. This process raises the temperatures in Jupiter's interior and atmosphere higher than would be expected purely from solar heating.