Physicists Kelvin and Helmholtz in the last century proposed that the source of the Sun's energy could be:

Question

Quizplus · Accepted Answer

Kelvin and Helmholtz proposed that the source of the Sun's energy was gravitational contraction, which is a process where the Sun would slowly contract over time, converting gravitational potential energy into heat. This theory, known as the Kelvin-Helmholtz mechanism, was considered before the discovery of nuclear fusion.

Physicists Kelvin and Helmholtz in the Last Century Proposed That