How to make a solar shadow observer

How to make a solar shadow observer is as follows:

1. Stick white paper on the blackboard and mark the southeast, northwest and south.

2. Fix the pencil vertically on the board and make a simple observation instrument.

3. Observe the position of the sun and measure the length of the pencil shadow.

Draw the shadow of the pencil on the white paper with a pen.

Expanding knowledge-Sun Shadow Observatory

In ancient times, the instrument that used the sun shadow to measure time was called a sundial. The sundial, also known as the sundial instrument, is an instrument for observing the time of the sun shadow, which mainly specifies the time or minutes at that time according to the position of the sun shadow. It is a widely used timekeeping instrument in ancient China. No matter ancient or modern, accurate time is indispensable. With accurate time, we humans can work and rest better, so the sundial played a great role in ancient times.

The sundial can display not only the time of day, but also the solar terms and months. Of course, its shortcomings are also obvious. It is huge and cannot be used when there is no sunshine, such as cloudy days and cloudy nights. This invention has been used by human beings for thousands of years, and it was not until 1270 that early mechanical clocks appeared in Italy and Germany.

Principle of sundial timing

The upper end of the needle points to the north celestial pole and the lower end points to the south celestial pole. 12 brick face is engraved with large squares on both sides, and each square represents two hours. When the sun shines on the sundial, the shadow of the sundial needle will be cast on the surface of the sundial, and the sun will move from east to west, and the shadow cast by the sundial needle on the surface will slowly move from west to east.

The scale of the coffin surface is uneven, so the moving shadow of the coffin needle seems to be the pointer of a modern clock, and the coffin surface is the surface of the clock to show the time. In the morning, the sun shadow is projected near Shi Mao at the western end of the disc, and then it moves northward (below) and gradually shortens.

When the sun reaches the highest position due south (upper meridian), the needle shadow is located due north (lower), indicating the local noon time. In the afternoon, the sun moves west and the shadow leans east, pointing to each hour in turn.