What is primarily observed in the length of shadows cast by a vertical stick when the height of the Sun changes throughout the day?

• A. A direct correlation between stick length and shadow length
• B. Variation in the compass direction of the shadow
• C. A consistent shadow length throughout the day
• D. No observable pattern in shadow length

Answer: (B)

The primary observation made in the length of shadows cast by a vertical stick as the height of the Sun changes throughout the day is the variation in the compass direction of the shadow. As the Sun rises in the east and travels across the sky to set in the west, the angle of sunlight changes continuously. This leads to the shadow being cast in different directions throughout the day.

In the morning, when the Sun is low on the horizon, the shadow of the stick will point away from the Sun, generally to the west. As the Sun rises higher in the sky, the shadow will shorten and begin to point more towards the north. At solar noon, when the Sun is at its highest point, the shadow will be at its shortest and point directly underneath the stick, or very close to it, depending on your geographical location. In the afternoon, as the Sun descends in the sky, the shadow will lengthen again, pointing towards the east.

This consistent change in direction and length of the shadow reveals the path of the Sun across the sky and illustrates the relationship between solar position and shadow orientation, making the observation of the shadow's direction the most significant point to note throughout the day.