Super Moon Phenomenon A supermoon is a full moon or a new moon that approximately coincides with the closest distance that the Moon reaches to Earth in its elliptic orbit , resulting in a slightly larger-than-usual apparent size of the lunar disk as seen from Earth. The name supermoon was coined by astrologer Richard Nolle in 1979, in Dell Horoscope magazine arbitrarily defined as: ... a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit ( perigee ). In short, Earth, Moon and Sun are all in a line, with Moon in its nearest approach to Earth. km