Wednesday, May 31, 2017



Before clocks and watches, people used the position of the Sun in the sky to tell the time. The instrument made to do this was called a sundial. It is thought that sundials were first invented in ancient Egypt and later improved upon by the Greeks and Romans. As technology advanced, clocks and watches took the place of sundials.

Sundials were used by many cultures to help the people know what time it was. When the Sun was directly overhead and the shadows of people and objects were at their shortest, it was said to be noon.

The Sun is highest in the sky at midday and casts a short shadow. In the afternoon, when the Sun is lower in the sky, the shadow is longer. The length of the shadow is also affected by the seasons. Winter shadows are longer than summer shadows. This is because the Sun is lower in the sky in winter.

You can tell the time by looking at the shadow cast by the Sun as it shines on the pointer of a sundial. The proper name for the pointer is a 'gnomon'. (This is pronounced 'nom-on') The flat surface of a sundial is called the dial plate. It may be made of metal, wood, stone, or other materials.

Most sundials just have marks for the daylight hours, when the Sun will actually cast a shadow. However, some show all 24 hours. The shadow cast by the gnomon when the sun shines follows a predictable path through the day. The path can be marked with hours to tell the time.

The predictable shadow path changes through the year. The reasons for this are that the Earth follows an elliptical orbit around the sun, and that the Earth's axis is tilted. As a result, the shadow cast by the gnomon moves at different speeds and to slightly different places at different times of the year.

Question Web

I wonder when it was invented
I wonder How often it is  used now
I wonder who invented it
I wonder how many years it  was used
I wonder how many Egyptians used it
I Wonder if they used in World War 2
I wonder how many shapes and sizes sundials are
I wonder how they used it in 1500 BC
I wonder when they start using the Sundial
I wonder if they've stopped using the sundial
I wonder in the future if they're still going to use sundials
I wonder how the sundial works at night

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