Page "New moon" Paragraph 3

The original meaning of the phrase new moon was the first visible crescent of the Moon, after conjunction with the Sun.

This takes place over the western horizon in a brief period between sunset and moonset, and therefore the precise time and even the date of the appearance of the new moon by this definition will be influenced by the geographical location of the observer.

The astronomical new moon, sometimes known as the dark moon to avoid confusion, occurs by definition at the moment of conjunction in ecliptical longitude with the Sun, when the Moon is invisible from the Earth.

This moment is unique and does not depend on location, and in certain circumstances it coincides with a solar eclipse.