Stonehenge was built and modified several
times over the course of a thousand years starting around 5,000 years ago. This kit shows what the final version probably
looked like based on the ruins that are there today. But some of these stones are simply missing
so archaeologists can’t know for sure that this plan was ever actually completed. These tall structures are called trilithons,
and the tallest one is 9 meters, or 30 feet. There’s only 3 of them still standing today, but it would
have been just two, except they propped one back up in the 1950s. These smaller stones are called bluestones. The geological source for these is over 200km
away, and there’s an ongoing debate about whether they were carried to the
site by people, or by glaciers some time long ago. Even these smaller stones weigh around 3 or 4 tons,
so it would be like moving 40 dead hippos from DC to Philly without a wheel. This is a prehistoric project, which means that the neolithic people that built it didn’t leave any written records about why or how they were doing this. But they did leave behind some clues, like
the antlers they used as picks to dig holes. Because antlers are organic material, they can
be radiocarbon dated, which is how archaeologists can estimate the chronology
of all of this. These outer stones weigh around
25 tons. Their source was more local, but they still
had to be moved some 20 km. and archaeologists can only guess how they did that. They’re called sarsen stones and they’re
harder than steel but they were shaped into these fairly uniform blocks using stone tools. And then they were pushed into pits before being pulled upright. The stones in the top ring are called lintels
and you can’t tell from this model but they actually had joints – like woodworking joints. There were grooves in the lintels that fit into bumps on the top of the upright stones and then on the side of the lintels, they also fit together like puzzle pieces. And not only that, but the neolithic builders who made this were able to carefully calculate the heights of all the stones so that the monument
was level even though it’s not on level ground. Grass! Ta- da! Except we’re not actually done. The stone circle was just part of the Stonehenge
site. It sits in a much larger circle that was drawn
in the earth with ditches and mounds. There was an avenue leading up to the entrance
of that circle, a big stone on that avenue called the Heel stone, and four other stones
that form a rectangle and may be linked to certain moon cycles. This site must have been incredibly important
to the neolithic people that built it, but despite hundreds of years of analysis and speculation,
we’ll never know for sure what it really meant to them. But we do know that it’s design involved
an early form of astronomy. In the 18th century, a historian noticed that
the central axis of stonehenge points toward the location on the horizon where the sun
rises on the summer solstice. So if you stood in the center of the monument and looked toward the Heel stone, you’d see the sun rise there on June 21st — it’s not
a perfect alignment, but it’s close. Summer solstice is when the sun’s path is
furthest north, rising in the northeast and setting in the northwest. That makes it high in the sky in the northern
hemisphere and low in the southern hemisphere. This is all because the earth is tilted relative
to it’s orbit around the sun, and the solstices are where the sun’s path appears to pause and change
direction. But the people that built stonehenge didn’t
know the earth moves around the sun or spins on a tilted axes. They probably didn’t even suspect it was
round. They just saw the sun bring longer days in
the summer and shorter days in the winter and those turning points would have meant a lot for their food security. And there’s reason to think that the winter
solstice was particularly important for the people at Stonehenge. The winter solstice sunset is on the same axis as the summer solstice sunrise – just on the other end, toward the southwest. And the midwinter alignment shows up in other monuments, like the
Newgrange tomb in Ireland which has a window that allows the sunrise to illuminate the inner chamber
on the sunrise of winter solstice. Archeologists also found pig bones from a
settlement near Stonehenge that they believe were slaughtered in the wintertime, based
on the pigs’ age. Their findings suggest an annual winter solstice pilgrimage and feast. The idea is that people would have approached the monument by walking on the avenue, which
would have put the midwinter sunset in their sightline, right in the window of the tallest
trilithon. Historian John North argued that when viewed
from this side, the monument’s silhouette would have looked like a solid black form,
with the setting sun bursting through bringing the promise of another spring. Video source: https://www.youtube.com/watch?v=Fx-KrvuiafE
