Humanity, and indeed all life on our planet, is sustained by the energy that has primarily been generated, on a large scale, through reactions between light atomic nuclei present in the Sun (thermonuclear fusion of hydrogen nuclei) and, on a much smaller scale, through what is known as nuclear fission (splitting of heavy nuclei, like those of uranium) occurring in the nuclear reactors of electricity-generating plants.

But, after all, since when and how did atomic nuclei become known? Who identified them as the ultra-small central region of the atom, concentrating all positive electric charge and virtually all atomic mass?

Exactly one hundred years have passed since the public announcement by New Zealand physicist and chemist Sir Ernest Rutherford (1871–1937), the discoverer of the atomic nucleus, at the meeting of the Manchester Literary and Philosophical Society in England on March 7, 1911.

This article revisits the main achievements that led scientists in the early years of the past century to conclude the existence of the atomic nucleus, the fundamental constituent of all matter in the Universe. The knowledge of the atomic nucleus and the resulting technologies have allowed modern humans to enjoy better health, comfort, and well-being.