Photo Descriptors - The Seattle, WA Equatorial Sundial ROW 1 No. 1 (SEA2.jpg) - The gnomon of a properly oriented equatorial sundial points toward the Celestial North Pole (CNP): the gnomon of the Webster Park sundial is capped with an Earth globe; the North Pole of the globe points toward the CNP. The gnomon should be parallel to the Earth's axis, inclined at an angle equal to the latitude of the observer. The dial plate should be parallel to the plane of the Earth's Equator (perpendicular to the gnomon), inclined at an angle equal to the complement of the observer's latitude. This angle is also known as the colatitude. The Seattle, WA sundial gnomon angle of inclination = ~48 degrees; dial plate angle of inclination = ~42 degrees. ROW 2 No. 2 (SEA6.jpg) - Upper dial face as viewed from the east-northeast (facing west-southwest). The dial plate is 30 inches in diameter; the Earth globe is eight (8) inches in diameter. Young woman shown for scale. No. 3 (SEA4.jpg) - The gnomon is the part of a sundial that casts the shadow used to tell time. For equatorial sundials, the gnomon is a pole (or rod) of varying thickness. The gnomon shadow falls on the upper dial face from the MAR Equinox to SEP Equinox (shown left); the gnomon shadow falls on the lower dial face from the SEP Equinox to MAR Equinox (see photo No. 10). On the day of the equinoxes, the declination of the Sun equals zero degrees (0°) and the Sun's apparent path across the sky follows the Celestial Equator. Since the dial plate of an equatorial sundial represents the plane of the Earth's Equator, the Sun is directly over the edge of the dial plate on the March and September Equinoxes, therefore the gnomon (or style) of a properly oriented equatorial sundial will not cast a shadow on the dial plate. No. 4 (SEA3.jpg) - Upper dial face as viewed from the north (facing south). The terrazzo surface of the dial face shows a crisp, hard-edged shadow! The sundial is designed so that time is told by estimating the center of the gnomon shadow. Photo taken on 01 JUN 1997; time shown = ~9:20 a.m. Local Apparent Time (L.A.T.) or ~10:17 a.m. PDT. The apparent discrepancy between solar time and standard time is caused by: 1) the Equation of Time (EoT); 2) the difference in longitude between the location of the sundial and the Standard Time Meridian (STM) for the Pacific Time Zone (PTZ STM = 120°W); and 3) Daylight Saving Time (DST). Note that the Webster Park sundial features a built-in correction for longitudinal offset from the Standard Time Meridian, therefore ~9:20 a.m. L.A.T. minus ~3 min EoT + 1 hr DST = ~10:17 a.m. PDT. ROW 3 No. 5 (SEA5.jpg) - Photo taken on 01 JUN 1997, nearing the date of the June Solstice, the first day of astronomical summer (meteorological summer is the three-month period from JUN-AUG). Note that the gnomon shadow does not fall on the lower dial face. Also note that the shadow of the dial plate falls along the segment of the gnomon that extends below the dial plate. No. 6 (SEA16.jpg) - View from the east-southeast (as indicated by Cardinal Points markers along base of sundial). No. 7 (SEA15.jpg) - View from the west-southwest (as indicated by Cardinal Points markers along base of sundial). ROW 4 No. 8 (SEA8.jpg) - The Earth globe is made of brass, approximately 1/4" thick. Relative to the Sun, the Earth globe is oriented just like Planet Earth. As a result, light and shadow on the globe appear the same as day and night on Earth (for the current time). The globe features the following lines of latitude (from north-to-south): Arctic Circle; Tropic of Cancer; Equator; Tropic of Capricorn; Antarctic Circle. Around the globe, there are 24 meridians or hour lines; every hour is exactly 15 degrees wide. On the Earth globe (as well as on Planet Earth), it is local solar noon when the Sun crosses Seattle's line of longitude. Relative to the sundial, the Earth globe is mounted on the gnomon so that Seattle's meridian is oriented 180° from the 12 noon PST hour lines shown on the dial faces (remember that shadows fall in the opposite direction as the Sun). No. 9 (SEA9.jpg) - The dial faces are marked to indicate Pacific Standard Time as well as Daylight Saving Time. Date markers appear as rings inscribed along the gnomon. Sundial motto (partially visible): 'We do not inherit this land from our parents, we borrow it from our children.' Native American Saying ROW 5 No. 10 (SEA11.jpg) - An afternoon gnomon shadow near the date of the December Solstice, the first day of astronomical winter in the Northern Hemisphere (meteorological winter is the three-month period from DEC-FEB). ROW 6 No. 11 (SEA12.jpg) - When the Sun's declination is negative (i.e., when the subsolar point is south of the Earth's Equator), the shadow of the dial plate falls along the upper segment of the gnomon (shown left). When the Sun's declination is positive (the subsolar point is north of the Equator), the shadow of the dial plate falls along the lower segment of the gnomon (see photo No. 1 & No. 5). No. 12 (SEA14.jpg) - DEC 20, near the date of the December Solstice. Sun glint from the surface of the Earth globe shows that the subsolar point is located south of the Equator, along the Tropic of Capricorn. Capricornus (DEC 22-JAN 19) is one of the signs of the Zodiac, the band of constellations through which the Sun, Moon, and planets move in the course of a year. Remember that signs of the Zodiac are 'Sun signs,' meaning that they appear in the day sky on your birthdate (the Sun is 'in' your sign). No. 13 (SEA13.jpg) - DEC 20. In addition to the dates of the equinoxes and solstices, the dates of important anniversaries (e.g., family birthdays) are often marked on sundials. DEC 20 is the birthdate of Mr. Nafziger's niece, which also marks the approximate date of the December Solstice. Other date markers include the birthdates of Chuck's children. ROW 7 No. 14 (SEA1.jpg) - Conceptual model of equatorial sundial displayed at public planning event for Webster Park, circa 1996. No. 15 (SEA10.jpg) - Sundialist Chuck Nafziger giving speech at Webster Park dedication ceremony, 01 JUN 1997. No. 16 (SEA7.jpg) - Smaller plaque, located on western side of sundial base (see photo No. 11), showing sundial title, location, and credits: EQUATORIAL SUNDIAL LATITUDE: 47 deg 40.7 min NORTH LONGITUDE: 122 deg 23.7 min WEST DESIGNED AND CONSTRUCTED BY CHUCK NAFZIGER A larger two-panel plaque, located on the eastern side of the sundial base (see photo No. 3), features detailed information regarding the sundial. Left panel section titles include: To Tell the Time; Sundial Description; Sun Time and Clock Time; Date and Daylight Features of this Dial. Right panel section titles include: Dial Time-Clock Time Conversion.