Why Can I Sometimes See the Moon During the Day?

Chloe Effron
Chloe Effron / Chloe Effron

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The Sun comes out in the morning and sets at night, and then the Moon rises. Right? Then how come we can see the Moon during the day sometimes?

The Moon and the Sun don’t actually take turns in the sky. The Earth orbits around the Sun, and the Moon orbits around the Earth. All three are spinning in space all the time. When the part of the Earth you're standing on faces the Sun, the sky is filled with sunlight. That's daytime. When your part of the planet is turned away from the Sun, that's night time. The Moon moves through the sky night and day. Much of the time, the sunlight is so bright, we can't see the Moon during the day.

The Sun is a very hot ball of gas. Like a fire or a light bulb, the Sun gives off both heat and light. But the Moon is made of rock, not gas, and it is not hot or bright at all. What we call moonlight is actually sunlight bouncing off the Moon, the same way that sunlight bounces off the reflectors on your bike. They look like they’re lighting up, but they’re really just passing the sunlight along.

How bright the Moon is depends on where it is in the sky. If the Moon is between the Earth and the Sun, it doesn’t bounce any sunlight to us at all, and it is very hard to see, even at night. This is called a new moon. When the Moon is behind the Earth, it shines very brightly. We call this a full moon. You can see in this video how the Moon gets different amounts of sunlight as it orbits around the Earth. That changes how it looks to us. Sometimes, when the Moon is very bright, we can see it even during the daytime.

Let's try an experiment! Tonight, get a flashlight and go into your room. (Bring your mom or dad with you if that seems a little scary.) Turn off the lights, and turn on the flashlight. You'll notice that it’s very easy to see the bright light of the flashlight. Keep the flashlight on, then turn the room lights back on. Now the light from the flashlight is a lot harder to see. It's the same with the Moon. At night, it’s easy to see the Moon, because it’s the brightest thing in the sky. But during the day, the Moon has to be very bright for us to notice it. That means that the best time to see a daytime moon is in the morning just before and just after the full moon.

To learn more about the Moon and light, visit the Science Trek Moon Facts web page.