Ancient Observatories


March 22, 2009, 1:33 am
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Mysterious rings of upright stones dot the hills and dales of England. The most famous is a monument called Stonehenge, which many people know only as a ring of giant stones standing silently in an ancient field. Few people realize that other prehistoric structures abound in the nearby landscape. For example, a broad "avenue" lined by earthen banks leads out of Stonehenge across the plains for about 1/2 kilometer (1/3 mile) toward the northeast. What was the purpose of such enigmatic features? In the Middle Ages, people believed that King Arthur's magician, Merlin, built them. Others attributed them to ancient wise men called Druids. In the 1720s, a lone scholar named William Stuckley visited many of the ancient monuments and made careful drawings of these prehistoric wonders. Stuckley was the first person to record a curious fact. The avenue leading from the center of Stonehenge points exactly toward the spot on the horizon where the Sun rises on the longest day of summer.

What could the alignment at Stonehenge mean? More than a century later, in the 1890s, English astronomer Norman Lockyer noticed that other ancient monuments were oriented according to astronomical principles as well. Lockyer rediscovered Stuckley's work and then synthesized it with his own observations to conclude that Stonehenge was a prehistoric astronomical temple designed specifically for ceremonies on the longest day of summer. According to Lockyer, ancient people from various parts of the world who lived from 3000 B.C. to 1000 B.C. knew of subtle astronomical cycles. For example, they knew how to construct calendars accurate enough to reliably plant crops from year to year. They knew of the variations in the motions of the planets among the stars. Some cultures were even able to discover that the constellations had subtly changed their shapes and positions over the centuries.

Archaeologists and other scientists of the day ridiculed Lockyer's ideas, arguing that ancient people could not have gained such extensive knowledge. Today, most scientists agree with Lockyer. Ancient architects in various cultures sometimes used astronomical knowledge to locate and orient buildings and monuments. We should avoid two tendencies when speculating about ancient cultures. The first is to assume that such people were unsophisticated because they had primitive technology. Remember that the brain function and language skills of humans have not changed for many thousands of years — the people who built Stonehenge were just like us. The second danger comes when we ascribe modern motives to ancient cultures. Stonehenge was not an observatory in the modern sense of the word. It almost certainly had a ceremonial and spiritual function as well. We can only make educated guesses at the intentions of the builders since they left no written language.

Building Stonehenge was a terrific undertaking! The circular embankment and solstice avenue were built around 2500 B.C. During the time that followed from 2100 B.C. to 1500 B.C., workers dragged the huge stones from quarries as far as 380 kilometers (240 miles) away and erected them to form the famous structure in the center of the ring. Archaeologists think that Stonehenge's purpose gradually shifted from precise observation to ceremony; by medieval times, its original function had been forgotten. Why would ancient people go to such enormous trouble to build this monument? Why would they take such an interest in the sky and astronomy? The sky serves as a map, a clock, and a calendar. The "cycles of the sky" have been important to every culture throughout history.

The landscape surrounding Stonehenge contains huge prehistoric monuments, stretching over several kilometres like the Stonehenge Avenue and the Cursus, massive earthwork enclosures like Durrington Walls and the North Kite, and hundreds of burial mounds. The whole World Heritage Site covers more than 2,600 hectares and includes 415 archaeological sites protected by scheduling. Many of the earthen monuments have been eroded away and often, only traces remain above ground. The Stonehenge World Heritage Site Interactive Map helps you discover this unique prehistoric landscape. 1


  1. Exploring Stonehenge,

External Links

  • Stonehenge –
  • Stonehenge - Interactive Map –
  • Stonehenge – HINODE/Solar-B, Marshall Space Flight Center, NASA. (Education Content: Dr. Sten Odenwald.)
  • Stonehenge – Dr. Christopher L. C. E. Witcombe, Professor, Department of Art History, Sweet Briar College, Virginia, USA.
  • Sunrise Solstice at Stonehenge – Astronomy Picture of the Day, June 21, 2006, NASA. ("Pictured, is the 2005 Summer Solstice celebration at Stonehenge in England. The event was rare because Stonehenge was not always open to the public, and because recent summer solstices there had been annoyingly cloudy. In 2005, however, thousands of people gathered at sunrise to see the sun rise through the 4,000 year old solar monument.")

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Stonehenge - HINODE/Solar-B, Marshall Space Flight Center, NASA.



Impey, Chris, Ph.D. (Contributing Author); Bernard Haisch (Topic Editor). 2009. "Stonehenge." In: Encyclopedia of the Cosmos. Eds. Bernard Haisch and Joakim F. Lindblom (Redwood City, CA: Digital Universe Foundation). [First published June 11, 2008].




(2009). Stonehenge. Retrieved from


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