Question

why is the moon sometimes out in the day

Answer 1

The moon sometimes appears during the day due to two reasons. First, the Moon is the closest celestial object to Earth.That is why it is the brightest object in the sky. The second reason is that specific nature of the Moon's orbit around the Earth. The reflected light from the Moon is so bright that it overpowers other sources of light in the sky.

Answer 2

The Moon is going around the Earth , all the time. The moon is only seen when it is up above our side of the Earth.The moon is visible to us as the light from the sun falls on it.
In the night, the moon seems to glow brightly as there is a dark black sky behind.
In the daytime also, the moon is still there shining brightly but we can't see as the sky behind is too bright. We hardly notice it