Is the moon all there?

[Rhw66]

When you get the chance to see a partial moon on a sunny day, why is it that you cannot see a black silhouette of the dark side of the moon?

[moorby]

You can only see the bright part of the moon by virtue of the sunlight reflecting off it towards our eye. The dark bit of the moon is the same colour as the background sky at night so you don't see it, because there is no transmitted image, ditto during the day. Sometimes you can see the dark part of the moon as slightly different colour from the rest of the night sky - I guess this is light from the Earth being reflected back.