Native Plant Park
Recycling  Composting  Enviro Club  Curriculum Integration  Phases  Plants  Do's and Don'ts  History
of Environmental Activities
Phases
Map
of Phase III
Equation
of Time
When
comparing sundial time to clock time, the times will be exactly the same
on some days of the year, but on the other dates they will differ slightly.
Why? Standardized clock time is based on the premise that the earth rotates
once (360 degrees) every 24 hours, every day of the year. Yet this is
not true. As the earth orbits the sun, it varies slightly in its speed
and its path. These slight variations result in some days being fractionally
longer than 24 hours, and some shorter, althought we standardize our clocks
so that each day is exactly 24 hours long. The difference between standardized
clock time and sundial time is called The Equation of Time. At certain
times of the year, sundial time may differ from clock time by up to 20
minutes. At other times of the year, when the Equation of Time is zero,
sundial time and clock time will be the same. To find out the value of
the Equation of Time for any particular day, again access the website
SunAngle, type in the particulars, and out will pop the Equation of Time
correction!
Details
of the Analemmatic Sundial
Installing
an Analemmatic Sundial
Equation
of Time
References
Appendix
