How does a shadow tell time?
Shadows change direction, depending upon the time of day. A Sun Clock like this one uses a shadow’s position to tell the time. Why doesn’t the time on my Sun Clock exactly match the time on my watch? The time you get from your Sun Clock is solar time, not standard time. The two aren’t exactly the same. According to solar time, it’s noon when the sun reaches its highest point in the sky. But the sun is always moving across the sky–which means that noon where you are is at a slightly different time than noon at a place a few miles to the east or west. Back before 1883, people used solar time. Each community kept its own time, basing that time on the sun’s position in the sky. Back then, noon in one town would be four minutes later than noon in a town fifty miles to the east. In 1883, to regulate time for the sake of railroad schedules, the United States adopted what is called standard time, designating time zones and requiring all communities within a time zone to keep the same time–ev
