Final answer:
Jupiter's internal energy sources are primarily from gravitational contraction and residual primordial heat, with minor contributions from radioactive decay. Nuclear fusion is not a source due to Jupiter's insufficient mass.
Step-by-step explanation:
Direct measurements indicate that Jupiter emits more energy than it receives from the Sun. The likely sources of this internal heat are primarily gravitational contraction and possibly radioactive decay. Gravitational contraction is the process by which the planet's mass slowly compresses under its own weight, releasing energy in the form of heat. This process, along with the retention of primordial heat from Jupiter's formation, accounts for much of the planet's internal energy source. Radioactive decay may also contribute to a minor extent by releasing energy as unstable atomic nuclei break down. However, unlike stars, Jupiter does not have a mass sufficient to initiate nuclear fusion in its core, and therefore, this is not a source of its excess energy. Magnetic field interactions, particularly synchrotron radiation, contribute to Jupiter's unique radio emissions but are not a primary driver of its overall internal energy budget.