The moon appears to have different shapes at different times. The changes that you notice in the moon’s appearance are called phases. Sometimes the moon looks like a dish. Sometimes it looks like a slice of fruit. But you know that the moon is really shaped like a ball. Only the amount of light reflected toward the earth changes.
What happens when the sun, moon, and earth are directly in line with one another? You see the moon as either fully lighted or mostly dark. You can see a full moon only when you are on the nighttime side of the earth.
During the new moon, the dark side of the moon faces the earth. For this reason, you can hardly see a new moon from the earth. Let’s follow the path of the moon through its monthly orbit around the earth.
A few days after a new moon, you see only a small curved part of the moon’s surface. What is the name of this lighted part? About seven days after the new moon, you see half the moon’s lighted surface. What is this phase called? As the moon keeps moving around the earth, you see more and more of its lighted surface. When the full circle of the moon is lighted, you see the full moon.
After the full moon, you see less of the lighted surface again. A few days later, you see a different half of the moon. How is this lighted part different from the lighted part in the earlier half moon? A few days later, more of the lighted side of the moon is turned away from the earth. After this phase, there is a new moon again.
Long ago, people noticed that a certain pattern was repeated, moon after moon, about every 29 days. Our world month is named after the moon.