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So, what in the world is Manhattanhenge, anyway?

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Two or three years ago on a pleasant summer evening, my husband and I went for a stroll. We started to cross the intersection at West 237th Street and Henry Hudson Parkway only to look up and see the most amazing sight. 

The sun seemed to be setting perfectly between the large buildings lining both sides of West 237th. My jaw dropped at the sight. And it was one of those rare occasions that I did not have a camera along and could not document the occurrence.

Since I did not document the date and time immediately, I was never certain when to check the intersection again for the next sighting.

We recently came back from a trip overseas to find a stack of unread newspapers on our doorstep.  While yesterday’s news is usually of minimal interest, science articles, sociology and human interest stories are always relevant.

One day, I finally opened The New York Times issue of May 29, finding a tiny box on the third page: “Manhattanhenge 2018: When and Where to Watch.” Knowing the monumental prehistoric Stonehenge construction in England, I was puzzled by its relevance to anything in Manhattan.

The 2018 summer solstice — from the Latin solstitium meaning “sun stopping” —  already took place June 21. The actual date apparently can vary between June 20 and June 22 due to the difference in time zones around the world as the solstice occurs sequentially. 

Another factor is calendar perturbations, particularly leap years, with their extra days in February.

At the two equinoxes, approximately March 21 and Sept. 22, day and night are of equal length. On those days, the sun rises due east and sets due west. After the equinox date in March, the sun rises a bit farther north of due east each day, and likewise sets the same bit farther north of due west until it reaches solstice, which is the farthest north the sun will travel in the sky. After the summer solstice, the sun will retreat a bit south each day for both sunrise and sunset, until it reaches the fall equinox — again rising due east and setting due west — and then continues travelling in a southerly direction until the winter solstice, its furthest southern point in the sky, when it will change directions and move northward again.

Manhattanhenge is clearly a takeoff on Stonehenge in Wiltshire, England. Although Stonehenge is the best known, there are other henges located throughout Great Britain, and somewhat similar structures throughout Europe. 

“Henge”  is a scientific term referring  specifically to large Neolithic (10,200 B.C. to 2,000 B.C.) structures featuring a ring bank and a ditch, with the ditch lying inside the bank. Oddly, it does not need to contain circular standing stones to qualify as a henge. Those that do are sometimes described as “circle henges.” 

In the case of Stonehenge, the ditch actually lies outside the bank.

Stonehenge is an elaborate complex built in several stages over a period of 950 and 1,500. Only the last stage, built between 2,400 B.C. and 2,000 B.C. contain the standing stones that are so famous. The only tools used seem to have been deer antlers for digging and stone tools to shape the upright stones. 

The two earlier phases involved creating the ditch, the embankment around the ditch, holes for timber posts, and even some cremation burials.

The first large stones erected at Stonehenge were the bluestones. Originally there were 80 of them, of which 43 are still standing. They are an igneous rock known as spotted dolerite, and because the rock cracks in a columnar fashion, it can be removed from the “mother” stone by inserting wooden wedges into cracks that then swell with rainfall and crack the stone completely away. The stones come from a quarry in the Presli Hills in Pembrokeshire, Wales, 140 miles from Stonehenge. 

The largest of the bluestones weighs three tons, and is nine feet tall.

Later the sarsen stones were erected outside the bluestones. The outer circle at Stonehenge, consisting of large upright stones with stone lintels joining the blocks together, is the “Sarsen Circle.” Sarsen is simply the name of the stone type used in its construction. It is a hard sandstone with the component sand being bound together by a siliceous cement. 

Some of these sarsen stones were raised in the very center and are called trilithons — two uprights supporting a lintel. The sarsens weigh around 40 tons and stand 24 feet tall. They most likely came from local quarries only about 25 miles away.

Hmm, how is the solstice involved in all this? See you next time!

Have a thought or comment for Sura Jeselsohn? Email her at greenscenesura@gmail.com.

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