Stonehenge is not only the most famous stone circle in Britain, but also the best-known ancient monument in the World, with at least ½ a million visitors each year. Located on Salisbury Plain, north of Salisbury, England, it is famous for the debate, mystery, and speculation surrounding it. Stonehenge was not built all in one single step, but rather in four separate stages, dating from approximately 3100BC to 1500BC. The modern visitor to Stonehenge is viewing the ruins of the final phase of construction site. The monument itself consists of four concentric ranges of stones. The oldest part, called Stonehenge I, consists of little more than a circular ditch dug in the chalky soil of the Salisbury Plain, with the soil taken from the ditch piled up to make an enbankment about 6 ft tall. This part of the monument is about 320 ft across. Inside this large circle are the things that we normally think of as Stonhenge proper; circles of stones that once stood upright, and the most photogenic, the large horseshoe arrangements of standing stones at the center. These last, the so-called trillithons, consist of upright stones supporting horizontal lintels, and the largest of them weigh in around 45 tons. These massive stones have been placed in unison with these circles to create Stonehenge and along with that bring about the curiosity of why one would build such a structure as that of Stonehenge.
The location of Stonehenge was not simply a coincidental happening, for the latitude is very specific in its function. In the Northern Hemisphere there is only one latitude for which, at their extreme declinations, the sun and moon azimuths are separated by 90º, and Stonehenge happens to be only a few miles from that latitude. At the latitude of Stonehenge, this axis crosses the midwinter sunset/midsummer sunrise axis at right angles. Every year on the first day of summer, the Sun rises at a point that is farther north than on any other day of the year. At the ruins of Stonehenge in England, this solstice sunrise appears on the horizon in direct alignment with the massive heel stone. This is the most outstanding feature of this ancient monument, built during the same era as the Great Pyramid of Egypt. There is little doubt that the builders of Stonehenge used it to mark this special day as the beginning of each year. By counting the number of days between these annual alignments, they could determine the length of the year. This could serve as a practical calendar to mark holidays and seasonal festivals and to ensure the timely planting and harvesting of crops. Six months after this the days would have grown shorter and air cooler, the midwinter sun sets, framed between the uprights of the Great Trilithon. This is the shortest day of the year, December 21st, and the Winter Solstice. A visitor standing in the center of the circle on the evening of the summer and winter Solstice would see the Sun setting above the Heel Stone. This would have been significant to those building Stonehenge because midwinter is believed to be the time when ceremonial help is most necessary ­ the Sun, the giver of life, has been growing weaker every day. It is the Winter solstice when things turn around, and the Sun would grow stronger once again. It is unknown whether the builders intended to use Stonehenge as a calendar to mark the changing seasons, or merely to symbolize their sun worship.
Stonehenge is also helpful in predicting solar eclipses. Many theorists support the idea that Stonehenge was used to predict successive eclipses. There are 19 upright columns in the monument’s center, which are collectively called the Bluestone Horseshoe. If the people present at Stonehenge placed some stone marker on top of a pillar at one end of the horseshoe during a lunar eclipse and moved the rock to the adjacent pillar at one end of the horseshoe during a lunar eclipse and moved the rock to the adjacent pillar every full moon, they could predict successive eclipses. If this movement were practiced every lunar month, the marker would stand at the center of the horseshoe after 2 ½ trips around the row, 47 months after the original eclipse. This would make sense being that eclipses are visible from certain locations on Earth in distinct 47-month cycles. This method would predict all lunar eclipses visible at Stonehenge, without predicting those that would not be visible from that location. Lunar Eclipses occur when the Sun is at one node and the Moon is at the other; this alignment can only occur during a full moon. With the situations of the structures present at Stonehenge those present would be able to predict the eclipses with the help of the monument.
Stonehenge is also given recognition for its reflection of the moons cycle. Some of the stones line up to point at the moon's rising and setting at special points in its 18.6-year cycle of movements. The astronomical alignments of Stonehenge, as they would have occurred about 3500 years ago, correspond to the Moon setting at its most Southerly point, Moon rising at its most Northerly point, the Sun rising at its most Northerly point and the Sun setting at its most Southerly point. These four alignments form an almost perfect rectangle, which is yet another fact that seems to be more than simply coincidental. Determining the length of the lunar month would have been necessary to predict eclipses. This is easily determined; it is simply the number of days between one full Moon and the next. This cycle of 29-1/2 days is marked at Stonehenge by two rings of 29 and 30 holes, which together average 29-1/2. Throughout these observations and the apparent knowledge of the ancient civilizations that constructed Stonehenge, many characteristics of the moon and its orbit were predictable.
Through the estimated 2,675,000 man-hours required to create Stonehenge it has definitely affected the cultures since the time of it’s arrival. As many hypothesized rumors of who created Stonehenge, these have been refuted on a very factual basis. As ancient rumor has it, Stonehenge was built postulates that Merlin the magician levitated the entire structure and transported it through the air from Ireland, where it had originally stood. Others hypothesized that extraterrestrials in flying saucers brought the stones to Stonehenge. Anthropologists were however in agreement that carrying, transporting and erecting the stones would be well within the technical capabilities of the people who lived around Stonehenge while it was being built. There is, in other words, no need to invoke either Merlin the Magician or extraterrestrials in flying saucers! With all of the theories acquired throughout the years pertaining to Stonehenge it is also quite assumable that the astronomical links were not simply coincidental. Whether for practical or religious reasons is unknown, but clearly the constructors of Stonehenge were very aware of the cycles our moon takes, and likewise the cycles of eclipses and equinoxes. Through the use of such monuments as Stonehenge many of these astronomical concepts have been taught and passed down through generations to help contribute to the vast knowledge we now have of such astronomical functions.