It is a universal fact the Moon does not produce light itself. It is the Sun who produces the light and the Moon brights from the Sun's light.
Because of the Moon's changing position as it orbits our planet, the Sun's light focus on different parts of it, giving the illusion that the Moon is changing shape over time.
But the fact is that the Moon never changes its shape. The shape of the Moon that appears at night, is the only part of the Moon which is facing us and in sunlight.
There are eight total phases of the moon cycle, four primary phases, and four secondary phases.
The primary phases are the new moon, first quarter, full moon, and last quarter.
The secondary phases are waxing crescent, waxing gibbous, waning crescent, and waning gibbous. The term waxing refers to the growth of the moon's image, while the term waning refers to a shrinking image.
The moon changes its shape every day. The day on which the whole of the moon is visible is known as the full moon day. Thereafter every night the size of the bright part of the moon appears to become thinner day by day.
On the fifteenth day, the moon is not visible. This day is known as the “new moon day”. On most days only a small portion of the moon appears in the sky. This is known as the crescent moon. Then again moon grows larger every day.
On the fifteenth day once again we get a full view of the moon The time period between one full moon to the next full moon is slightly longer than 29 days (~29.5 days). The various shapes of the bright part of the moon as seen during a month are called phases of the moon.
