The sun and sister moon are sharing the sky today. I wonder why the moon is not silvery, like at night?

Answer 1

It's all a question of contrast. During the night, the Moon is sitting in a black sky, so appears much brighter (and if you're outside in the dark your eyes have adapted, making it even brighter). During the day the Moon and sky are about the same brightness, and your eyes are adapted to bright conditions, so the Moon doesn't appear so bright.

Of course, in reality it's reflecting the same amount of light, so it's just as bright during the day as it is later at night, but the different viewing conditions alter your perception of it.

Answer 2

Because the Moon has no light of its own, at night it merely reflects the Sun which is on the other side of the planet but during the day and both are in the same hemisphere, the sun is too bright to let the Moon show its usual level of luminescence. It is after all just an over grown dusty rock.

Answer 3

The moon is low in the horizon and you are looking at it through the atmosphere

Answer 4

moon's light is reflected light whreas sun is giving its own light,
some times when both appear in day time, moons light cannot dominate sunlight.

Answer 5

and first thing this morning venus was visible too, a hattrick!