Sundial

:This article pertains to the astronomical instrument. For the psychedelic rock band, see Sun Dial.

Related Topics:
Psychedelic rock - Sun Dial

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A sundial measures time by the position of the sun.

Related Topics:
Time - Sun

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The most commonly seen designs, such as the 'ordinary' or standard garden sundial, cast a shadow on a flat surface marked with the hours of the day.

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As the position of the sun changes, the time indicated by the shadow changes.

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However, sundials can be designed for any surface where a fixed object casts a predictable shadow.

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Most sundial designs indicate apparent solar time.

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Minor design variations can measure standard and daylight saving time, as well.

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Sundials are known from ancient Egypt, and were developed further by other cultures, including the Greeks and Romans. The mathematician and astronomer Theodosius of Bithynia (ca. 160 BC-ca. 100 BC) is said to have invented a universal sundial that could be used anywhere on Earth. The French astronomer Oronce Fine constructed a sundial of ivory in 1524. The Italian astronomer Giovanni Padovani published a treatise on the sundial in 1570, in which he included instructions for the manufacture and laying out of mural (vertical) and horizontal sundials.

Related Topics:
Greeks - Romans - Theodosius of Bithynia - Oronce Fine - Ivory - 1524 - Giovanni Padovani - 1570

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