In 1913, the Danish physicist Niels Bohr proposed a model of the electron cloud of an atom in which electrons orbit the nucleus and were able to produce atomic spectra. These difficulties cast a shadow on the planetary model and indicated that, eventually, it would have to be replaced. Furthermore, Rutherford's model was unable to describe how electrons give off light forming each element's unique atomic spectrum. If the electron circling the nucleus in an atom loses energy, it would necessarily have to move closer to the nucleus as it loses energy, and would eventually crash into the nucleus.
This is, after all, how we produce TV signals. It was already known that when a charged particle (such as an electron) moves in a curved path, it gives off some form of light and loses energy in doing so. Unfortunately, there was a serious flaw in the planetary model.
\): Niels Bohr with Albert Einstein at Paul Ehrenfest's home in Leiden (December 1925).
