Celestial Timekeeping
This page was written by Jenny Deupree, who has a degree in Astronomy, and has been interested in megalithic astronomy since her first visit to Stonehenge in 1964. How to use the astronomy of sun and moon to draw the 7-circuit labyrinth, was learned from the artist Aidan Meehan, who also taught us Celtic knotwork. The diagrams and drawings were done by Jenny for her book: The Feminine of History is Mystery. For more information, see Jenny’s Blog.




is based on the annual cycle of the sun, the cycles of the moon, and the way these cycles are reflected in changes in weather and patterns of growth on the planet earth. The civil year is an arbitrary way to order the days that is convenient for governments, business, landlords, etc. The sacred year is much more closely tied to actual experience.

The sacred year is much older than the civil year. Sacred timekeeping probably began with somebody, most likely a woman, noticing that the moon goes through cycle after cycle in roughly the same number of days. After keeping track for a number of months, it begins to be obvious that the time interval from new moon to new moon is about 29.5 days. Nomadic people, following herds and flocks, and seafaring people, concerned with tides and fishing, would find the cycles of the moon gave them useful information. The seasons of the sun would be less important.

The next step came after people settled down and lived in the same place for long enough to begin to observe the changes in the position of sunrise on the eastern horizon and its correlation with the weather. If you had a fixed watching point and a clear eastern horizon, you would begin to see a regular cycle. In the summer, when the weather is hot and the days long, the sun rises in the northeast section of the horizon. In winter, with cold weather and short days, the sun is rising in the southeast quadrant. From this kind of observation came our division of the year by the four solar holidays: Spring Equinox, Summer Solstice, Fall Equinox, Winter Solstice.

As an astronomer, I have been interested in the sacred year for a very long time. After visiting Stonehenge and reading The White Goddess in 1964, I became interested in the “Fire Festivals”, and curious about their astronomical origins. The “Fire Festivals” are also known as the “Cross Quarter Days” and their traditional dates are May 1, Beltane, August 1, Lammas or Lughnasad, November 1, Samhain (pronounced Sa-wain), and February 2, Imbolc. These dates are still remembered in our culture with May poles and Hallowe’en costumes, and even Ground Hog Day may record a memory of measuring the seasons by the shadow of a pole or standing stone.

Actually, the traditional dates are misleading. Initially I thought that perhaps they were a memory of the time when the first of the month meant the new moon, and so would indicate the new moon farthest from solstice or equinox. But the layout of Stonehenge gives a different suggestion. Stonehenge is aligned not only to the solstices and equinoxes, but also to the standstills of the moon, a phenomenon rediscovered by Gerald Hawkins when he did his computer study of Stonehenge.


The lunar standstills are nowhere near as easy to observe as the stations of the sun. In order to get any idea of what is going on, an astronomer would have to carefully observe the moon through a period of about 19 years, and only after at least three such cycles (56 years) could one get any sense of a pattern. There are signs at Stonehenge of a series of post holes which appear to be the relics of a century of observation of the winter full moon’s risings between the solstice point and the major standstill. See WIKIPEDIA for more information about the LUNAR STANDSTILLS.

To understand the dating of the Cross Quarter Days, you need only know that for each solstice point on the horizon, there are two standstills of the moon. For the summer solstice sunrise, the “Major” Standstill is to the north of the sunrise point, a place where the sun never rises. The “Minor” Standstill is to the south of the solstice, a place where the sun rises around the beginning of May on its way to Summer Solstice, and around the beginning of August on its way back to Fall Equinox. At Stonehenge, the sun appears in the arch of the minor standstill at these times. A similar arch for the Minor Standstill associated with the winter solstice frames the sunrise at the beginning of November and again at the beginning of January.


The earth’s North Pole is tipped 23°26′ from the North Pole of the Ecliptic. Another way to say this is that the earth’s axis of daily rotation makes an angle of 23°26′ to its axis of revolution around the sun. Because of this tilt, we experience four seasons in temperate latitudes. On the Summer Solstice in the Northern Hemisphere, the Sun is 23°26′ North of the Celestial Equator, rising in the Northeast, setting in the Northwest, traveling its longest path through the sky. On the Winter Solstice in the Northern Hemisphere, the sun is 23°26′ South of the Celestial Equator, rising in the Southeast, setting in the Southwest, traveling its shortest path through the sky. The exact compass direction of the extreme sunrises and sunsets depends on the latitude. (In the Southern Hemisphere the seasons are reversed, their summer is our winter, etc.)

The Moon’s standstills show a similar but more complex pattern of extremes. The moon’s orbit is tilted 5°15′ with respect to the earth’s path around the Sun. The orbit also changes position, moving in a complete cycle in 18.61 years. This means that about every 19 years, the moon’s tilt adds to the earth’s tilt in such a way that the moon, at the highest point of its path, is 23°26′ + 5°15′ = 28°41′ north of the celestial equator. It will rise well to the north of the summer solstice sunrise. At the highest point in its path, the moon will be at 0° Cancer, the same zodiacal longitude as the sun on the Summer Solstice. About two weeks later, the moon will be at 0° Capricorn, the lowest part of its path, and stands at 28°41′ south of the celestial equator.

Since the moon travels through 0° Cancer once every month, theoretically there would be many chances to observe its rising point on the horizon. In practice, this would be very difficult to do except when the moon is nearly full and at 0° Cancer which occurs at midwinter. (These are the positions of the post holes found at Stonehenge marking horizon points north of the summer solstice point.) The lunar major standstill represents not so much a point in the sky or a position of the moon, but a window of opportunity.

In 2006, the position of the moon’s orbit meant that the moon was passing through these extremes, and interested astronomers calculated the best times and places to observe the moon. I went with a group from Findhorn to the stone circle of Callanish on the Isle of Lewis in the Outer Hebrides. We went in May, hoping to see one of the lowest moons of the year pass behind the stones. Alas, it was rainy and cold, but we were there among the stones, singing our songs, on May 15 at 1:15 AM. It didn’t even matter that we didn’t see the moon, just to be there felt like being part of the great cosmic dance. (See Jenny’s trip to CALLANISH.)

Corresponding to major standstill is minor standstill which happens about 9.3 years after major standstill, when the moon’s tilt subtracts from the earth’s tilt, and the moon at 0° Cancer, its highest point, is only 23°26′ – 5°15′ = 18°11′ north of the celestial equator and at 0° Capricorn it’s at 18°11′ south of the equator. At this time, the moon at its two extremes is well within the sun’s extremes. This means that after a period of observation long enough for several cycles of the moon a neolithic astronomer could point out a place on the eastern horizon that belonged to the minor standstill, and even set up two standing stones as a sight line. Once this place is marked, it can be seen that the sun rises at this point some time between Equinox and Solstice, and again on its way back.

More detailed discussion & calculations can be found at Victor Reijs’ website.

In the summer half of the year, the dates when the sun arrives at 18°11′ north are May 13 and August 1. The corresponding winter dates are November 15 and January 29. At Stonehenge, trilithon arches marking the Lunar standstills were set in the central horseshoe. The rising sun would shine through these arches on these dates: May 13, August 1, November 15 and January 29. This is strong support for the idea that these dates were the original dates of the Cross Quarter days. (Of course, the people who built Stonehenge did not have the months of November or May, but they did have seasons counted from the sun’s rising in a particular place.)