Daytime moon: Why can we sometimes see the moon in broad daylight?

The nearly-full daytime moon hangs dimly in a blue sky near clouds.

The moon's presence in the night sky has transfixed people for millennia. But why is the moon sometimes visible during daylight?

We sometimes see the daytime moon for the same reason we see it at night — it is reflecting light from the sun — and its closeness to Earth makes it brighter than the daytime or nighttime sky. After the sun, the moon is by far the brightest celestial object we can see.