Tracking the Sun (Explanation)

When we marked the center of the Sun's reflection on the wall every ten minutes, the marks formed a straight line. The movement of the marks indicate the Earth's rotation.

The Earth rotates on its' axis roughly every 24 hours. The axis is an imaginary line which runs through the north and south pole of the Earth. The axis is tilted 23.5° with respect to the plane of the Earth's orbit.

It is the rotation of the Earth that makes the Sun (and the moon, planets and stars) appear to move across the sky. We see this movement demonstrated by the movement of the Sun's reflection on the wall.

When we marked the Sun's reflection each day at noon, a different line formed. If you performed this experiment in the Spring, your daily noon line would be higher each day in autumn and lower each day in the spring.

The daily change in the Sun's noon position is caused by the Earth moving around the Sun. The Earth makes one trip around the Sun each year. As the Earth moves around the Sun, the tilt of its axis affects our seasons.