Why is the shadow of an object shortest at noon?

The shadow of an object is shortest at noon because the sun is at its highest point in the sky, directly overhead or close to it, depending on the season and latitude. When the sun's rays strike the object more vertically, the angle of the light reduces the length of the shadow cast. As the sun moves lower in the sky during the morning and afternoon, the angle of the light becomes more oblique, resulting in longer shadows.