Aim: How do we measure time? The Sun Aim: How do we measure time?

I. Apparent Motions of the Sun A. Shadows- a shadow is very long at sunrise, decreases in length as the morning progresses, is shortest at noon, and increases in length throughout the afternoon.

Shadows Continued… 1. An object’s shadow always points directly away from the sun.

a. Example If the sun is to the south at noon, the shadow points to the north.

B. Our System of Time Apparent Motions- the motion of celestial objects, such as the sun, the moon, or a planet through the sky. The object is not really moving as it appears to be. a. We base our system of time on the apparent motion of the sun. The apparent rising and setting of the sun is based upon the Earth’s rotation.

II. Seasons- Equinox-the time at which the sun is directly above the equator, sunlight lasts for 12 hours, they mark the first day of spring and fall. Solstice-the longest or shortest day of the year when the sun is directly above the Tropic of Capricorn or Tropic of Cancer. They occur in December and June and mark the beginning of the winter and summer.