8 Responses. > 1  the Moon takes an elliptical path around the Earth. The planets make nearly elliptical orbits around the Sun, close enough for reasonable approximations, but the Moonâs Orbit around the Earth is sufficiently influenced by the Sun that it follows a path detectably different from an ellipse.
Quick Answer. In 1896, French scientist Antoine Henri Becquerel discovered radioactivity which was an early contribution to atomic theory. He discovered this phenomenon while experimenting with uranium and a photographic plate. Continue Reading.
But it was really the 1890s when scientists began looking at radioactive elements. Henri Becquerel and the Curies, and they started looking at-I love this-subatomic particles. First we say the atom is indivisible, but then we know there's protons, neutrons and electrons and so on, and then things kept going and going. And of course most notoriously was the atomic bomb on Hiroshima and Nagasaki.