Perry County Missouri
(panel 1 - Eclipse
This sundial commemorates the total solar eclipse
that occurred here on August 21, 2017, starting with a partial eclipse at 10:51:05 solar time (11:53:43 AM CDT), reaching a peak of totality at 12:20:04 solar time (1:22:41 PM CDT), and ending with a partial eclipse at 13:46:23 solar time (2:49:01 PM CDT).
Shadow-paths traced by the tip
of the triangular-shaped gnomon follow four datelines on the sundial. On December 21 each year, the shadow of the tip follows along the line labeled Southern Solstice
(or winter solstice).
On March 21 and September 23, it follows the Equinox
line. On June 21, the shadow of the tip follows the Northern Solstice
(or summer solstice) line.
Each year, the shadow-path of the tip brings to our memory the total eclipse by moving along the Eclipse
line on August 21. As the tip traverses the Eclipse
dateline, it encounters markers at the times of the onset, the peak of totality, and the end of the eclipse event that occurred here.
(panel 2 - Time
This sundial shows solar time
. The hour marked 12 indicates solar noon — the time when the sun at this location reaches its highest elevation of the day, 1 indicates one hour after solar noon, etc.
the time shown on your watch or cellphone on the day of the eclipse, August 21, add 1 hour, 2 minutes, and 40 seconds to the solar time shown by the sundial. Read the explanation below to understand why.
Three factors relate the time indicated by this sundial to civil time - the time indicated by your watch or cellphone.
This relationship is
t CIVIL = t SUNDIAL
+D - L - EOT
= +1 hour when "daylight savings time" is in effect and 0 when not. L
accounts for the difference between the longitude 89.86°W of the dial's location and the longitude 90°W used for Central Standard Time; this difference of 0.14° implies that L
is 40 seconds. EOT
stands for "Equation of Time." This accounts for the earth's noncircular, tilted orbit around the sun. EOT
depends where the earth is in its orbit around the sun, that is, on the date, as seen here graphically.
(panel 3 - Sundial
Design. Donald L Snyder
of St. Louis, a Member of the North American Sundial Society
and the St. Louis Astronomical Society
, designed the sundial. It commemorates the occurrence in Perry County, Missouri, of the Great American Eclipse
on August 21, 2017. Trish Erzfeld, Director of Perry County Tourism
, coordinated the project and served as an enthusiastic supporter.
Sundial. Abraham Mohler
, St. Louis sculptor and artist, made the dial plate.
Gnomon. William Turner
, of Turner Associates in St. Louis, made the gnomon.
Pedestal. Earth Works Inc.
made the pedestal of limestone they quarried in Perry County.
This sundial is located at the Perry County Courthouse in Perryville, Missouri. Extensive renovation of the Courthouse was completed in time for its celebration with this sundial on August 19, 2017, the weekend of the total solar eclipse.