Sundial

A sundial is a device that tells the time of day 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 across 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, a wire or an 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 the horizontal is equal to the sundial's geographical latitude.

In a broader sense a sundial is any device that uses the sun's altitude and/or azimuth to show the time. In addition to their time-telling function, sundials are valued as decorative objects, as literary metaphors and as objects of mathematical study.

Sundial (disambiguation)

Sundial or sun dial may refer to:

Places

Music and literature

Other

Man Enters the Cosmos

Man Enters the Cosmos is a cast bronze sculpture by Henry Moore located on the Lake Michigan lakefront outside the Adler Planetarium in the Museum Campus area of downtown Chicago in Cook County, Illinois, United States. The planetarium, which is both a National Historic Landmark and listed on the National Register of Historic Places, is located in the Near South Side community area of Chicago. Moore's sculpture is a functional bowstring equatorial sundial created in 1980 measuring approximately 13 feet (4.0 m). The sundial was formerly located slightly further south at the steps of the main entry plaza to the Planetarium, but it now sits directly on the lakefront. The work is a later copy of a composition first created in the 1960s for the offices of The Times newspaper at Printing House Square in London, and according to the Henry Moore Foundation is titled Sundial 1965-66 .

Details

The sundial has two plaques on its base. The one on the left is a commemorative one discussing the benefactor and purpose of the sculpture. The benefactor of the sculpture was the B.F. Ferguson Monument fund, which has commissioned several works of art throughout Chicago. Many of the Ferguson fund's commissioned works, such as the Fountain of the Great Lakes, are housed in and on the grounds of the Art Institute of Chicago or elsewhere in Grant Park. The purpose of the commission was to recognize the space exploration program. The plaque on the right is an equation of time table to correct for the time differences caused by the axial tilt of the Earth as well as its orbital eccentricity. As the plaque indicates with an additional correction, the equation of time table does not correct for daylight saving time.