I was about a month early to photograph it on the actual solstice but that is OK, I hadn't planned on doing that anyway. But with this shot, you get the idea.
The info on this particular stone:
"This was the first monolith suspected to be a solar alignment. After extensive research it was photographed at sunset on December 21, 1970 (shortest day of the year) by Robert E. Stone. This stone marked the southern most set of the sun 4,000 years ago, but it is off today because of the Earth's tilt (obligity) has changed."
More info on the site:
"HOW DOES IT WORK?
The astronomical calendar at America's Stonehenge marks many important days in ancient cultures. These includes the Solstices, Equinoxes, Cross Quarter Days as well as a True North Alignment.
The term Solstice means "sun stands still". On summer solstice (the longest day of the year) which falls around June 21st and Winter Solstice (the shortest day of the year) which falls around December 21st, the sun will rise over one monolith and set over another. The same thing happens on the Equinoxes. The equinoxes occur when the sun is over the equator. On those days daylight and darkness are equal meaning 12 hours of daylight and 12 hours of darkness. The equinoxes are approximately March 21 and September 21.
The cross quarter days mark the days between the solstices and equinoxes. Old Celtic calendars observed Cross Quarters. Unlike modern calendars that define the start of a season on a Solstice or Equinox, the Celts perceived Solstices and Equinoxes as events occurring mid-season, with the seasons actually beginning and ending on the Cross Quarters.
You may have noticed that many of these ancient holidays fall very close to many holidays we see on our calendars today. Some of the cross quarter days we've adapted into our calendar are February 1st which is now groundhog day or candlemas, May 1st or May Day which although not celebrated as much these days was a big holiday for many around the world, November 1st has been adapted as Halloween and Christmas falls within a couple of days of the Winter Solstice.
USING THE ASTRONOMICAL CALENDAR TO DATE THE SITE
The astronomical alignments at America's Stonehenge are very useful in determining the time period that the site was built. Due to the earths tilt, the alignments are slightly off. The degree that the sun is off on these stones is a dating technique we use to figure out when the stones were put into place.
OTHER ANCIENT OBSERVATORIES
There are many other ancient observatories throughout the world including Easter Island, Stonehenge in England, The Temple of Karnak and Pyramid of Giza in Egypt, Machu Picchu in Peru, Chichen Itza in Mexico, Calendar I and II in Vermont, The Gungywamp in Connecticut and America's Stonehenge to name just a few."