A new moon is the first lunar phase in astronomy, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the naked eye, except when it is silhouetted against the Sun during a solar eclipse. Here are some key points about new moons:

• The original meaning of the term new moon, which is still sometimes used in calendrical, non-astronomical contexts, is the first visible crescent of the Moon after conjunction with the Sun. This thin waxing crescent is briefly and faintly visible as the Moon gets lower in the western sky after sunset.

• The astronomical new moon 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.

• New moons occur approximately once every month because thats roughly how long it takes for the moon to orbit Earth. But because the moons orbit is slightly tilted relative to Earths orbit around the sun, it doesnt block out the sun on every orbit, hence why not every new moon results in a solar eclipse.

• New moons are generally completely invisible without special equipment and a lot of moon-photography experience. However, some people use the term new moon for a thin crescent moon visible in the west after sunset. Astronomers don’t call these little crescent moons new moons, however. In the language of astronomy, this slim crescent is called a young moon.

• The Moon guides the dates of many religious and cultural holidays around the world. For example, the new moon is the beginning of the month in the Chinese calendar, and in some cultures, it defines the beginning of the months in the Islamic calendar.