From Encarta online we get this:
I had no idea that there were over 1,000 henges throughout the British Isles.
They knew something we don’t know they knew. That’s pretty cool.
Cartooniverse
We’ve also had a Staff Report on Stonehenge.
We’re pretty sure that one of the purposes of Stonehenge was to track the summer solstice: Lots of cultures have shown an interest in the solstices and equinoces, and the Summer Solstice is the primary alignment of the Henge. If you stand right in the center of the horseshoe area on the morning of the Summer Solstice, you’ll see the Sun rising right on top of an outlier stone of the formation, called the “Heel Stone”. But the Henge is a lot more sophisticated than it would need to be to just mark the Solstice-- for that, you’d only need two markers (one to show where to stand, and the other to show where the Sun rises relative to that vantage point). It’s possible that the stones mark many other dates in a similar manner, but we have no idea what particular dates would have been significant to the builders, and there are so many possible pairs of stones one could choose that we have no way of reconstructing them. It’s possible that the other stones held some religious significance, but again, we know so little about the culture that erected the stones that we can’t say what that significance might be. And it’s possible that there is no actual significance to the other stones, and they’re just there for decoration.
This explains the otherwise-baffling phrase in the Qur’an verse 55:17, “the two easts and the two wests.” The literal meanings of the words translated as “east” and “west”–mashriq and maghrib–are ‘place of sunrise’ and ‘place of sunset’. Doubling each of them refers to the different locations of sunrise and sunset at the solstices, as the endpoints of a range of positions.
Maybe someone already suggested this, but you and your son could go aout an not where the sun sets relative to some landmark on the horizon. The sun is going south quite rapidly right now and the motion should show up in a couple weeks of observing. Maybe even less. Just make a note to go look one day, then a day a week later, then two weeks and so on.
Also, on December 22 note the location of sunset on the horizong and again on June 22.
That’s a lotta stone to hump around the British Isles just to tart up the look of the place a bit, isn’t it? The chronology ( heh. heh. ) of the construction is important. WHEN various elements were put in place tells the story. The real Henge ( see below ) came first. It predates the first circle of bluestones by what, 1,500 years? You also mentioned not knowing much about the culture that erected the stones. To be fair, there were cultures that erected them. The total construct time of the inner ring, outer ring and placement of other stones of great importance such as the Heel Stone along the main lane out to the river, took several thousand years.
The link I put in did mention something fascinating- and it answers something you said in your post.
The true Henge is not the stones. There are Henges all over the British Isles- that is the dug in circle, with the dirt removed as they dug piled up to raise up a hump all around the rim of the circle. The holes found- named Aubrey Pits for the man who first noted them- can be used not only for things as relatively banal as predicting the next solstice, but for calculating future astronomical events such as solar eclipses. This is extremely brilliant stuff and speaks of an understanding of astronomy, geometry and such.
IMHO, the entire construct and use do not speak to Druids, or religion, or anything outside of the realm of science. 5,000 years is a veeeeeeerrrrrrry long time to hew to a single religious concept. In fact, I cannot think of a culture we are aware of that has hewn to a religious concept for that long. To me it is a remarkable bit of science and as most of us will admit, science is immutable.
The same very clever Neolithic peoples who first designed the Henges and made them workable items had their work expanded upon by latter generations who built the bluestones and the sarcen stone constructs.
To me the awe comes from a sharp humbling. We’re not so smart. We’re no smarter than the Neolithic peoples who created a calculator the size of a farm, to predict solar eclipses and other astronomical events.
Maybe not completely safe to say that.
In principle the Sun could set in exactly the same place two days in a row, if the sunsets were bracketed just right around the moment of a solstice — that is, if the sunsets were spaced 12 hours before and after the moment of solstice, for the observer’s location.
A perfect fit will essentially never happen, but a fit that’s close enough to be measureably the same might happen on human time-scales.
Sure, if you consider “several times every six months” to be a human time-scale. For about a week bracketing the solstices, the movement will be inperceptible to the naked eye (plus or minus, depending on how good your landmarks are, and how perceptive your particular eye is).
Cartooniverse, don’t read too much into “Stonehenge could have been used to predict eclipses”. Any set of landmarks could, in principle, be used in the same way, provided that there’s enough of them, and that you have the mathematical sophistication to know how to use them. The fact that Stonehenge is sufficiently populated with landmarks (stones, postholes, etc.) in no way implies that the builders had that level of mathematical sophistication. Of course, it also doesn’t imply that the builders didn’t have that level of sophistication; we just don’t know.
I can think of several religions which have persisted for 5,000 years, but I can’t think of a single scientific idea which is known to have persisted for that long. And there’s nothing to say that there was a single religion behind Stonehenge, either: Religions have a great tendancy to incorporate and assimilate the holy places of other religions. Heck, we even see it at Stonehenge itself: Modern-day neo-pagan Druids worship at that site, despite having no particular connection to the earlier cultures that built it. Why couldn’t some earlier culture who discovered Stonehenge and had no idea of its history have reacted similarly?
By “measureably” in my post, I meant measureable with instruments.
The technical term for that is Dip. It just depends if Astro is more of a dip than his son. 
In standard navigation techniques, one meter of added height is considered significant enough to be measured. This compounds itself if you are navigating from the deck of a large ship some 20-30 off the water. If you don’t account for dip, you can be off by miles.
Throughout architecture school we often used Sun Path Diagrams.
They’re very usefull and actually easy to read.
Of course you have to find one for your correct latitude location.
Here’s one for London
On the circle 90 degrees represents due east, 180 degrees represents due south, and 270 degrees represents due west.
If you look at the line marked “1st Jun” you’ll see that the sun rises almost directly in the northeast at almost 5 a.m. and sets almost directly in the northwest at 9 p.m… The sun at it’s highest point that day will be 60 degrees above the horizon.
The opposite extreme would be for January 1st. The sun would rise almost directly southeast at 9 a.m. and set almost directly southwest at 5 p.m. The highest the sun would ever get that day would be 15 degrees above the horizon.
A great tool for architects for figuring sunlight and shadows throughout the year.
The OP has a very observant child as many adults don’t even notice the subtle changes in position of the sun and moon.
Consulting ephemeral data posted in the World Almanac, you will find that near the summer solstice, for one, there is a case where the sun’s declination (in short, its position in the sky) virtually does not change as it remains at +23 degrees 26 minutes for a few days (around June 21) before descending southward. The same stagnant apparent motion can be observed around Dec 21 before the sun begins moving northward once more.
Nope. I used to have a bedroom where, in the winter, I could see the sun’s whole path from the bed. In the summer, I still saw its rise (further to the right, not enough to be covered by the nearest building) but not its set (which moved to the left enough to not be seen from the bed).
It’s at about 44ºN
Most modern cameras are designed NOT to be able to take multiple exposures, but if you can come up with an old fashioned one and put it on a tripod, and manage not to disturbe that tripod over several days, the kid could take an exposure at the same time every morning, (or evening) this would not only teach something about the sun’s motion but would be a great lesson in patience, persistance, and delayed gratification. A homemade pinhole camera would work great, just make sure it is totally light tight.
It does stretch the mind a bit to imagine that thousands of worker bees, over several thousand years, went to all of that effort without the science to understand why they were placing huge stones exactly where they were placing them, but were perfectly willing to place them there anyway.
And, following that line of thought, whomever it was that passed the master plans along through the generations could have done so with no idea at all of what the final outcome should be in terms of design or function? That’s also very hard to believe. In fact, I cannot think of another man-made item on the planet of that scale that exists in a vacuum, with no plan or goal at all.
No offense, bit it is hard to figure out.
Maybe it’s just supposed to be art.
What makes you think there was a master plan? So far as I know, there were no records, other than the henge itself, communicated between the various cultures who added to the structure.
Well… because I struggle with the idea of such extreme exertion over thousands of years, solely for art. And I’m an artist !!!