1, the stars and the moon actually exist during the day and at night, but the sunlight is too strong during the day, so they are basically invisible. Because the moon itself does not shine, it can only shine through the reflection of the sun's light, so it is difficult to see the moon when you can see the sun during the day.
2. The generation of day and night is the result of the earth's rotation. Suppose you are at point a of the earth. When point A turns to the side where the sun shines, point A enters the daytime at this time, and people at the opposite point A can see the sun.
3. When point A enters the side that is not illuminated by the sun, it enters the night. At this time, the moon is illuminated by the sun and people can see it at night. The shape of the moon is influenced by the position between the moon, the earth and the sun.
During the day, if the moon is between the sun and the earth, there will be an eclipse. At this time, the sun will be covered by a shadow, and the shadow is the moon.
When the earth is between the sun and the moon, an eclipse will happen. The shadow of the sun on the earth blocked part of the light reflected by the sun, resulting in a missing piece of the moon.