Sundial facts for kids

A sundial

A garden sundial at 9:30am

A sundial shows the current solar time during the day. It does this because the sun appears to move through the sky. At different times in the day when the sun is shining, a shadow is cast in different places on the dial. A person marks the dial with the time at a certain shadow. This lets users easily see the time. There are a few commonly seen designs, such as the 'ordinary' or standard garden sundial. However, sundials can be designed for any surface where a fixed object casts a predictable shadow.

Ancient Egypt had sundials. Other cultures developed them further, including the Greeks and Romans.

Related pages

Time

Images for kids

In this sundial, in Melbourne, Australia, the gnomon is the triangular blade. The style is its inclined edge.
SSW facing, vertical declining sundial on Moot Hall, Aldeburgh, Suffolk, England. The gnomon is a rod that is very narrow, so it functions as the style.
A combined analematic-equatorial sundial in Ann Morrison Park in Boise, Idaho, 43°36'45.5"N 116°13'27.6"W
A child and a woman look at a sundial in the National Gardens of Athens, Greece
Top view of an equatorial sundial. The hour lines are spaced equally about the circle, and the shadow of the gnomon (a thin cylindrical rod) rotates uniformly. The height of the gnomon is 5/12 the outer radius of the dial. This animation depicts the motion of the shadow from 3 a.m. to 9 p.m. (not accounting for Daylight Saving Time) on or around Solstice, when the sun is at its highest declination (roughly 23.5°). Sunrise and sunset occur at 3am and 9pm, respectively, on that day at geographical latitudes near 57.05°, roughly the latitude of Aberdeen, Scotland or Sitka, Alaska.
Sundial in Singapore Botanic Gardens. The fact that Singapore is located almost at the equator is reflected in its design.
World's oldest sundial, from Egypt's Valley of the Kings (c. 1500 BC)
Southern-hemisphere sundial in Perth, Australia. Magnify to see that the hour marks run counterclockwise. Note graph of Equation of Time, needed to correct sundial readings.
The Whitehurst & Son sundial made in 1812, with a circular scale showing the equation of time correction. This is now on display in the Derby Museum.
Sunquest sundial, designed by Richard L. Schmoyer, at the Mount Cuba Observatory in Greenville, Delaware
full-size image]] reveals the "spider-web" of date rings and hour-lines.
Horizontal sundial in Minnesota. June 17, 2007 at 12:21. 44°51′39.3″N, 93°36′58.4″W
Detail of horizontal sundial outside Kew Palace in London, United Kingdom
"Double" sundials in Nové Město nad Metují, Czech Republic; the observer is facing almost due north.
Polar sundial at Melbourne Planetarium
Effect of declining on a sundial's hour-lines. A vertical dial, at a latitude of 51° N, designed to face due South (far left) shows all the hours from 6am to 6pm, and has converging hour-lines symmetrical about the noon hour-line. By contrast, a West-facing dial (far right) is polar, with parallel hour lines, and shows only hours after noon. At the intermediate orientations of South-Southwest, Southwest, and West-Southwest, the hour lines are asymmetrical about noon, with the morning hour-lines ever more widely spaced.
Two sundials, a large and a small one, at Fatih Mosque, Istanbul dating back to the late 16th century. It is on the southwest facade with an azimuth angle of 52° N.
Vertical reclining dial in the Southern Hemisphere, facing due north, with hyperbolic declination lines and hour lines. Ordinary vertical sundial at this latitude (between tropics) could not produce a declination line for the summer solstice.
Commons annotations]] for labels.
Analemmatic sundial on a meridian line in the garden of the abbey of Herkenrode in Hasselt (Flanders in Belgium)
19th century Tibetan Shepherd's Timestick
Declination lines at solstices and equinox for sundials, located at different latitudes
Diptych sundial in the form of a lute, c. 1612. The gnomons-style is a string stretched between a horizontal and vertical face. This sundial also has a small nodus (a bead on the string) that tells time on the hyperbolic pelikinon, just above the date on the vertical face.
Benoy Sun Clock showing 6:00 p.m.
A bifilar dial showing the two wires
Noon mark from the Greenwich Royal Observatory. The analemma is the narrow figure-8 shape, which plots the equation of time (in degrees, not time, 1°=4 minutes) versus the altitude of the sun at noon at the sundial's location. The altitude is measured vertically, the equation of time horizontally.