Niels Henrik David Bohr (7 October 1885 – 18 November 1962) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922. He developed the model of the atom with the nucleus at the center and electrons in orbit around it, which he compared to the planets orbiting the sun. He worked on the idea in quantum mechanics that electrons move from one energy level to another in discrete steps, not continuously. Bohr mentored and collaborated with many of the top physicists of the century at his institute in Copenhagen. He was part of the British team of physicists working on the Manhattan Project. Bohr married Margrethe Nørlund in 1912, and one of their sons, Aage Bohr, was also a physicist and in 1975 also received the Nobel Prize.