And at midnight.
What does it mean? It means the shadow is painted in to the wall, it is not cast by the light of the sun since it does not move with the sun. The shadow should move through the day like a sun dail.
When you walk in to the shadow you are not covered in it. This shadow was lovingly placed on the arch to make up for the fact that the SL sun sits in the sky but does not give light. The sun is only a kind of clock, telling how much light the environment will have but not making it so. And the light just exists in SL, it does not come for anything. Light is about us like oxygen is about it. Its a world full of electricity like RL is full of oxygen.