Why can't I see the moon in the sky sometimes?

Because the moon shines by reflecting sunlight, its relative position with the sun is different (longitude difference), so it will take on various shapes. As shown in the figure, at the position of 1, the longitude difference between the sun and the moon is 0, which is called new moon or crescent moon. At this time, the moon faces the earth with a black face, which appears almost at the same time as the sun, so it can't be seen on the ground. /pic/ 16/ 1 159956443247262 . jpg