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How do I Calculate Solstices?

The solstices are a celestial event marking both the longest and shortest solar days of our calendar year. As the earth revolves around the sun, it tilts on its axis, and the sun shifts locations on the horizon creating a traceable record of the seasons. When it reaches its most northern or southern point on our horizon it appears to stand still at its zenith, or solstice, before beginning to move back in the opposite direction. Archeological sites such as Stonehenge show this event has been tracked since ancient times, and with some calculating you can find the solstice for your location.

Things You'll Need

Latitude of your geographic location
Pencil and paper
Optional: Computer with internet connection
Optional:Solstice calculator website

Instructions

Hand Calculation
- 1
  Determine the latitude of your location.
- 2
  Add 23.5 degrees to your latitude for the winter solstice calculation in the northern hemisphere, subtract 23.5 degrees for the southern hemisphere. The axis of the earth tilts us either closer or further away from the sun, and in winter we are closer by about 23.5 degrees in the northern hemisphere and further away by that measurement in the south. In the opposite season the degrees are switched.
- 3
  Subtract your answer from 90 degrees to get the angle of the sun above the horizon. For example, if your latitude was 52 degrees north, your formula for the winter solstice would read 52 + 23.5 = 75.5, then 90 - 75.5 = 14.5 as your angle of the sun above the horizon on the solstice. For summer, reverse the formula.
Plug in Calculators
- 4
  Locate a solstice calculator website such as Stellafane: Equinox and Solstice Calculator, or Codeguru..
- 5
  Choose the year you want to determine the date and time of the solstice.
- 6
  Click calculate to receive the results. Some calculators are more in depth and use detailed time and location measurements to give you the exact time of the 'sun standing', or the moment when the sun has reached the zenith for that solstice.

Astronomy