sundial

Also known as sun dial

thumb|right|SSW facing, vertical declining sundial on the Moot Hall in Aldeburgh, Suffolk, England. The gnomon is a rod that is very narrow, so it functions as the style. The Latin motto loosely translates as "I only count the sunny hours." [[File:Melbourne sundial at Flagstaff Gardens.JPG|thumb|right|A horizontal dial commissioned in 1862, the gnomon is the triangular blade. The style is its inclined edge.

AI overview

A sundial is a device that uses the shadow cast by a rod or blade (called a gnomon) to indicate the time of day as the sun moves across the sky. Sundials were historically important timekeeping instruments and remain valued today as decorative and functional markers that remind us of humanity's long relationship with observing the sun's passage.

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Wikidata facts

Image: Got the time^ - geograph.org.uk - 1469342.jpg

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Commons category: Sundials
Commons gallery: Sundials
OpenStreetMap tag: display=sundial

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~75 min read

Article

55 sections

Contents

Introduction
Apparent motion of the Sun
History
Functioning
In the Southern Hemisphere
Adjustments to calculate clock time from a sundial reading
Summer (daylight saving) time correction
Time-zone (longitude) correction
Equation of time correction
With fixed axial gnomon
Empirical hour-line marking
Equatorial sundials
Horizontal sundials
Vertical sundials
Polar dials
Vertical declining dials
Reclining dials
Declining-reclining dials/ Declining-inclining dials
Empirical method
Spherical sundials
Cylindrical, conical, and other non-planar sundials
Movable-gnomon sundials
Universal equinoctial ring dial
Analemmatic sundials
Foster-Lambert dials
Altitude-based sundials
Human shadows
Shepherd's dial – timesticks
Ring dials
Card dials (Capuchin dials)
Navicula
Nodus-based sundials
Reflection sundials
Multiple dials
Diptych (tablet) sundial
Multiface dials
Prismatic dials
Unusual sundials
Benoy dial
Bifilar sundial
Digital sundial
Globe dial
Noon marks
Sundial cannon
Meridian lines
Sundial mottoes
Use as a compass
Notes
References
Citations
Sources
External links
National organisations
Historical
Other

thumb|right|SSW facing, vertical declining sundial on the Moot Hall in Aldeburgh, Suffolk, England. The gnomon is a rod that is very narrow, so it functions as the style. The Latin motto loosely translates as "I only count the sunny hours." thumb|right|A horizontal dial commissioned in 1862, the gnomon is the triangular blade. The style is its inclined edge.

A sundial is a horological device that tells the time of day (referred to as civil time in modern usage) when direct sunlight shines by the apparent position of the Sun in the sky. In the narrowest sense of the word, it consists of a flat plate (the dial) and a gnomon, which casts a shadow onto the dial. As the Sun appears to move through the sky, the shadow aligns with different hour-lines, which are marked on the dial to indicate the time of day. The style is the time-telling edge of the gnomon, though a single point or nodus may be used. The gnomon casts a broad shadow; the shadow of the style shows the time. The gnomon may be a rod, wire, or elaborately decorated metal casting. The style must be parallel to the axis of the Earth's rotation for the sundial to be accurate throughout the year. The style's angle from horizontal is equal to the sundial's geographical latitude.