Lunar phases Phases of the Moon as it orbits Earth, showing the angle formed by the position of the Moon with respect to the Sun at each phase. (more) new moon lunar phase Written by Erik Gregersen Erik Gregersen is a senior editor at Encyclopaedia Britannica, specializing in the physical sciences and technology. Before joining Britannica in 2007, he worked at the University of Chicago Press on the... Erik Gregersen Fact-checked by Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Britannica Editors Last updated June 5, 2026 •History new moon, one of eight lunar phases, in which the Moon is between Earth and the Sun, and thus the side of the Moon that is in shadow faces Earth. The new moon is traditionally regarded as the first phase in the lunar cycle. The cycle of lunar phases lasts close to a month, at 29.5 days, a period known as the synodic month. Thus, the new moon typically occurs once per calendar month, but when...

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