The moon is the brightest thing we see in the night sky, but it looks different every night. This is because of the moon’s phases, which make it seem like it’s changing shape. Let’s learn about why this happens by exploring how the Earth and the moon move in space.
The moon travels around the Earth, just like the Earth travels around the sun. While the Earth takes about 365 days to go around the sun, the moon takes about 29.5 days to go around the Earth. This is about one month, which is why the words “moon” and “month” are related.
Even though the moon looks bright, it doesn’t make its own light. It shines because sunlight hits it and bounces back to us. The moon has a day side and a night side, with half of it lit up by the sun and the other half in darkness. As the moon moves around the Earth, the line between day and night, called the terminator, shifts. This makes it look like different parts of the moon are lit up each night.
The moon’s phases start with the New Moon. During this time, the moon looks completely dark because the side that isn’t lit is facing us. A solar eclipse can only happen during a new moon because the moon is between the sun and the Earth.
As the moon moves, we start to see a small sliver of light called a Waxing Crescent. “Waxing” means the moon is getting brighter. This crescent grows bigger each night until it becomes the First Quarter moon. This is also called the half moon because it looks half-lit, but it’s actually one-quarter of the way through its cycle.
Next, the moon enters the Waxing Gibbous phase. “Gibbous” means “humped” or “swollen,” and the moon keeps getting brighter until it becomes a Full Moon. The full moon is the biggest and brightest phase, rising at sunset and staying up all night. A lunar eclipse can happen during a full moon because the Earth’s shadow can cover the moon.
After the full moon, the moon starts to get smaller, becoming a Waning Gibbous. “Waning” means the moon is getting dimmer. The next phase is the Third Quarter, also called the last quarter, where the moon is three-quarters of the way through its cycle.
Finally, the moon becomes a Waning Crescent, getting smaller until it disappears completely, starting the cycle over with the New Moon.
The moon, with its big, bright, and beautiful phases, is a wonderful sight in the night sky. Its cycle repeats every month, making it a great object to watch and learn about. Next time you look at the moon, try to figure out which phase it’s in and guess what phase will come next!
Moon Phase Diary: Start a moon phase diary! Every night, look at the moon and draw what you see in a notebook. Write down the date and what phase you think the moon is in. After a month, look back at your drawings and see how the moon changed. Can you predict what phase will come next?
Moon Phase Cookies: Use cookies to create the different phases of the moon. You can use a round cookie as the full moon and then take bites to create the other phases like the waxing crescent, first quarter, and so on. Arrange them in order and see if you can explain each phase to a friend or family member.
Shadow Play: Use a flashlight and a ball to create your own moon phases. In a dark room, shine the flashlight on the ball and observe how the light creates different shadows on the ball. Move the ball around to mimic the moon’s orbit around the Earth and see how the phases change. Can you make a full moon or a new moon?
