Why is the same side of the moon always visible to earth

One side of the moon always faces Earth because of what's called synchronous rotation. That is, the moon rotates, or spins on its axis, in the same length of time it takes to orbit Earth. ... For that reason, our moon always has one side facing Earth, which we call the moon's near side

radiative zone

explanation    

radiative zone is the layer of the sun which energy is transferred away from the core by radiation. although, the core is the only part of the sun that produces an appreciable amount of heat through fusion. in fact, 99% of the energy produced by the sun takes place within 24% of the sun's radius.