How does a sundial tell time? Detailed answer

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How does a sundial tell time? Detailed answer

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How does a sundial tell time?

The sun was the first clock for man. Long ago, man determined what time it was by looking at the sun as it moved across the sky. It was easy to distinguish between sunrise and sunset, but it was much more difficult to know the time when the sun rose above the horizon. It was during these daylight hours that it was difficult to tell the time, guided by the sun.

The man noticed that the length of the shadow changes throughout the day. It became clear that the time could be more accurately determined by looking at the shadow rather than at the sun. This discovery was only one step away from the invention of the sundial, which is actually a shadow clock. Instead of trying to look at the sun and associate the time of day with it, it is better to look at the shadow, which reflects the position of the sun in the sky. The first sundial was simply a pole stuck into the ground.

Stones placed around the pillar showed the position of the shadow as it moved throughout the day. So a person could measure the current time. Later they began to use huge stone columns. Cleopatra's Needle, now on the Thames in London, is part of such a sundial. But smaller sundials were also used. One small Egyptian clock, which is 3500 years old, is in the shape of the letter L. It lies flat on the long side of this letter, and the marks show 6 periods of time.

About 300 BC. e. the ancient Babylonian astronomer invented a new type of sundial, shaped like a bowl, a ball. The shadow cast by the pointer moved and marked 12 hours a day. This type of sundial was very accurate and has been used for centuries.

Sundial can be seen in the gardens nowadays, but it was built more for entertainment than for real use. However, crude sundials can sometimes be seen on walls and window shutters. They are designed so that the crutch or edge of the window casing casts a shadow.

In an accurate sundial, the pointer should be placed at an angle equal to the latitude of the place where the clock is used. Just a vertical stick shows the correct time only at a certain latitude, at a certain time of the year. If the dial is flat, the hour markers should be unevenly spaced on it.

Author: Likum A.

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