Solar eclipse and Einstein. Computer illustration of the Swiss-German physicist Albert Einstein (1879-1955) next to the Moon in front of the Sun during a total solar eclipse. Solar eclipses occur when the Moon passes between the Sun and the Earth and fully or partially blocks the Sun. Einstein received the 1921 Nobel Prize for Physics for work on the photoelectric effect. However, he is best known for his paper on the special theory of relativity, which resulted in the famous equation E=mc2.