The phenomenon of visibility of the moon is really observed in a new moon. It occurs owing to some reasons. The side of the Moon which is lit with the Sun every time addresses inhabitants of Earth under a new corner therefore change of lunar phases appears. This process is not influenced by Earth shadow, except those moments when the Moon is eclipsed during a full moon. Such phenomenon occurs twice a year.
During a new moon the Moon and the Sun interact as follows: the satellite of Earth is combined with the Sun therefore the consecrated part of the Moon becomes invisible. After day it can be observed in the form of a narrow sickle which gradually increases. Such period usually is called the growing Moon.
During the movement of the terrestrial satellite along the orbit in the first quarter of a lunar cycle the visible distance of the Moon from the Sun begins to develop. A week later after approach of a new moon, the distance from the Moon to the Sun becomes just the same, as well as distance from the Sun to Earth. At such moment visible is a quarter of a lunar disk. Further the distance between the Sun and the satellite continues to grow that is called the second quarter of a lunar cycle. At this moment of Long is on the most remote point of an orbit from the Sun. Its phase at this moment will be called a full moon.
In the third quarter of a lunar cycle the satellite begins the return movement concerning the Sun, approaching him. The decreasing Moon decreases to the size of a quarter of a disk again. The lunar cycle comes to the end with the fact that the satellite is returned to a starting position between the Sun and Earth. At this moment the consecrated part of the Moon completely stops being the planet seen for inhabitants. In the first part of the cycle of Long arises in the morning over the horizon, together with a rising sun is in a zenith by noon and in a visible zone for all day before calling of a star. Such picture is usually observed in tropical and subtropical belts. Thus, each appearance of a lunar disk depends on a phase in which there is a celestial body at any given moment. In this regard there were such concepts as the growing or decreasing moon and also the blue moon.