sundial
Sign in to savethumb|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.
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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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Article
55 sectionsContents
- 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.