The Human Sundial

The Human Sundial. Discover Rockville in Your Own Backyard. , The Shadow Stick , Sundials date back to the Greek shadow stick known as the gnomon (no-mon), which is Greek for "the one that knows." When people began to notice that shadows grew shorter or longer depending on the time of day, the shadow was used to view the shadow to help measure time and determine the time of day., How Does A Sundial Work , As the earth turns on its axis, the sun appears to move across the sky. The shadows the sun cast move in a clockwise direction for objects in the northern hemisphere. The elliptical rotation of the early does not allow the sun to rise and set in the same time and location, therefore shadow sticks were not accurate clocks. Eventually people discovered that angling the gnomon and aiming it north made a more accurate sundial. The analemmatic sundial is a horizontal sundial that has a vertical gnomon and hour markers positioned in an elliptical pattern. The gnomon is not fixed and must change position daily to accurately indicate time of day. Hence there are no hour lines on the dial and the time of day is read only on the ellipse. As with most sundials, analemmatic sundials marker solar time rather than clock time. An An analemmatic sundial is completely defined by the size of its ellipse (chosen by the designer, the latitude of its location determines the location of the hour markers on the ellipse), and the declination of the sun (determines the daily gnomen position). In the analemmatic sundial, the gnomon moves to adapt to the time of year and corresponding angle of the sun., What Time Is It? , To determine the time of day using the human sundial, you must become the gnomon, or vertical object that casts the shadow for the time. To begin, first locate the stone that corresponds with the current month. Standing on the appropriate stone, you will be facing north and your shadow will be cast in the direction of the Roman numerals making up the "clock" or sundial. During daylight savings time the result will be an hour behind the actual time., Who Constructed It? , This analemmatic sundial was built by Boy Scout Troop 447 and friends and family of Danta Natle, who planned, designed and supervised its construction for his Eagle service project. It took more than 30 volunteers and 159 hours to complete over three days. The sundial's Roman numerals are recycled bricks from the trolley system that ran through Rockville from 1900 until 1935., Thank you to the many volunteers that helped create this sundial for the whole community to enjoy.