is noticed ( since 18th century ) that the horseshoe of great trilithons and the
horseshoe of 19 bluestones opened up in the direction of the midsummer
sunrise. It was quickly surmised that the monument must have been deliberately
oriented and planned so that on midsummer's morning the sun rose directly over the Heel
Stone and the first rays shone into the center of the monument between the
open arms of the horseshoe arrangement.
The midsummer sun always rises exactly opposite the setting of the midwinter sun - thus an alignment with one is an alignment with the other, unless some feature blocks on of the alignments.
The relationship between Stonehenge and the SUN :
may NOT accidental
It was argued that the summer solstice alignment could not be accidental. The sun rises in different directions in different geographical latitudes. For the alignment to be correct, it must have been calculated precisely for Stonehenge at its latitude of 51° 11'. Therefore, The alignment must have been fundamental to the design and placement of Stonehenge.
The alignment also made it clear that whoever built Stonehenge had precise astronomical knowledge of the path of the sun. Moreover, it must be known before construction began precisely where the sun rose at dawn on midsummer's morning while standing on the future site of the monument. This point needs to be made because, as suspected by some archaeoastronomers, it was the site ( a particular place within the landscape that the Stonehenge ), that was important. Only later were these sites marked in some more permanent manner by the digging of ditches and banks and erects of wood or stone structures.
Stonehenge: Phase I
The builders of Stonehenge had observed much more, however; although sunrise on Midsummer's day was probably the most important ceremonially, other alignments( See Construction ) have also been found that are agreed to be too accurate to be mere coincidences.
However, it would be very cumbersome to keep track of the rising position of the suns because of precession whereby the changes are not noticeable. Hence, the argument that the relationship between the Stonehenge and the Sun is not accidental may be overruled.
may NOT be true
Despite some strong photographic evidence, some astronomers feel that the Sun does not quite rise exactly above the Heel Stone as viewed from inside the stones. They state that all those lovely photographs showing the midsummer sun rising above the Heel stone are a con trick - the sun has already risen and is part of the way on in its journey round the sky. However, apart from this fact, the Heel stone had a partner, and when the partner was still standing, the midsummer sun would have been framed by this pair of standing stones as the first rays of dawn shone through a stone corridor into the heart of Stonehenge.
from the center of Stonehenge towards the Heel
Stone, and a photograph of the sun rising over the Heel
could be used as a calendar
Hoyle proposes that the Aubrey holes were used as a sort of calendar, recording the Sun and Moon's orbits about the Earth, as if they must have appeared to prehistoric man. For the calendar to work, it must have a starting point. The Sun's cycle would have started about Midsummer's day, although the actual Midsummer rising of the Sun is measured by the Heel Stone. Hence, the importance of determining accurately the very point of Midsummer would mean alignments would have to be measured both before and after this event. This would minimize the risk of missing Midsummer's day due to bad weather or some other reason.
At Stonehenge other alignments do exist on the Southerly side of the most Northerly rising point (just South of Midsummer's day position). It appears to Hoyle that the position of the Sun can be accurately determined at least once each year. A marker on the Aubrey holes would be set in its first position on this day. The moon cannot be set in the same as its cycle of 18.61 years would be too long to keep an accurate calendar. If however they realized that when the moon was full it was directly opposite the Sun, the Sun's marker could be used to set the Moon marker. (Markers are also discussed briefly in the ‘Moon’ section) It would be placed 28 holes around from the Sun marker on the first full Moon after Midsummer's day and then checked each following full Moon.
This gives us two markers on the ring of Aubrey holes, one representing the Sun and one representing the Moon. For this calendar to work someone would have to move the Moon marker anticlockwise two holes each day; this means that a complete circle would be made every 28 days (just over the actual time it takes the Moon to orbit the Earth ). The Sun marker would be moved in an anticlockwise direction by one marker every 13 days. This is quite a complicated procedure to keep going just to keep an accurate calendar. Nonetheless, the had proven its usefulness in agriculture in ancient times.
could be used to predict eclipses
If though we introduce the idea that the Aubrey circle representing the ecliptic and add two more markers that represent the nodes at which the Moon crosses the Ecliptic, then the circle could become a more powerful eclipse prediction tool.
This is just one theory of the purpose of Stonehenge. There are many problems with this theory. One of the main ones being that the eclipses would rarely have been visible from the Stonehenge area it does however raise questions about the purpose of Stonehenge and the time over which it was built.
Showing Circles & Banks
and some alignments.