Have you noticed how your health can take a dip at certain times of the year? We find ourselves getting autumn or spring colds for example. Every autumn I used to develop a cough that wouldn’t go away, and Julian Barker, our herbalist, started to tell me about ‘mid-points’ – days during the year at roughly the mid-point between the solstices and equinoxes. During these days our health could suffer as the season changed. I realised that these mid-points correlated roughly with the cross-quarter festival times – the Celtic fire festivals of Imbolc, Beltane, Lughnasadh and Samhain. How interesting! They occurred around 6th Feb, May, August and November. So here is a phenomenon that links our physiology with these ancient festival times. I asked Julian if he would write a Mount Haemus paper for the Order about this, which you can find here, and you can watch a videoclip of Julian introducing his paper here.
Recently Julian has sent me his depiction of the calendar, illustrating the midpoints, together with a brief explanation which I think you will find fascinating…
THE PHOTIC CALENDAR by Julian Barker
Meteorologists determine the start of each season by the average local weather rather than other climatic considerations. So in a conventional calendar, the first day of March is heralded, at least in Britain, as the first day of spring even though the vernal equinox is only three weeks away; likewise, June the 1st is taken to be the beginning of summer even though it too is only three weeks before the solstice that marks the actual middle of summer. In making August part of summer rather than autumn, meteorologists are more in tune with our usual weather and culture, but they make no sense from an astronomical, solar, point of view.
By contrast, here you will find a calendar built upon day-lengths: the solar structure of the year. These photic cues (rather than temperature alone) trigger the seasonal hormonal shifts that affect all living creatures and on which human health depends. Critical changes in day-length go some way to explaining why February and August have always shown peaks in hospital admissions for certain conditions. The ganglion cells in our retinae are photovoltaic cells and reset thermostats in our metabolism on a seasonal basis.
The solstices and the equinoxes represent the sun’s apparent movement: being overhead at each of the two tropics at 23.5 degrees of latitude in June and December, then turning back, crossing the zero degree of the equator in March and September when days and nights are equal. These four—solar limits and crossing points—identify the true middle of each of the four seasons. We should calculate their starting point midway between them. True: the weather will always lag behind, because it takes time for the atmosphere and oceans to heat up and cool down.
If we take the four seasons to be roughly equivalent in length, it follows that the start of each season is not that of the weather–forecaster but is to be found at the midpoint intervals that lie equidistant between these four solar events. These four transitional midpoints—in February, May, August, November—show the true start of each of the four seasons and are highlighted in my calendar on the 6th of each of those months. These days might be hot or cold and more like the season that immediately preceded it, but plants and migrating birds have to look ahead and plan for breeding and feeding. They use increasing or decreasing day-length to do so. We share their hormonal systems so, even if we reach for overcoats, scarves & gloves or sun-hats, swimsuits & sunscreen before we venture out into the local season, our metabolism is not so persuaded by today’s weather alone. I have elaborated these physiological ideas in a paper written for the Order of Bards, Ovates & Druids and delivered as their 12th Mount Haemus Lecture in 2012.
Throughout the year, the actual lengths of complete day/night cycles are not equal because of the eccentricity of earth’s orbit. Calendars try to squeeze these unequal day-lengths into equal–sized boxes. We create these human devices for our own purposes: to accommodate the fact that measurements of the tropical and sidereal year do not match exactly and neither one constitutes a whole number of days. They are our best approximations and why we have leap years to prevent our numbered years drifting apart from astronomical reality, as happened historically between the Old Roman, the Julian and the Gregorian calendars, forcing the British Parliament to shave off eleven calendar days in 1752. With all necessary caution in any search for temporal exactitude, I present my calendar as an approximate guide to our physiological seasons.
The dates read upwards in columns from the winter solstice as the days lengthen, and downwards from the summer solstice as they shorten. Most of the columns are a week tall. The four transition points of each season are shown in bold, as are solstices and equinoxes. Just as the days lengthen and shorten so our metabolism builds and repairs our structure (anabolism) and breaks down foodstuffs (catabolism). Of course we metabolise all the time but night, winter and summer favour increased anabolic activity while day, spring and autumn favour increased catabolic activity.
This photic calendar is easy to read: the summer solstice at the top and winter solstice at the bottom divide the year into two halves along the vertical central axis (column zero), with the weeks and days between them ranged in 19 columns of days to the left (ascending daylight–lengths) and 19 columns of days (descending daylight–lengths) to the right side. As with any calendar, each square holds a day of a month. For ease of reading off any date from a column, each row is numbered, from one to 33.
It allows you to spot today’s place (as well to read off your birthday and other significant days) on the rising or falling wings of the year and their closeness to the potentially triggering midpoints. At the same time, it allows you to locate the day of equivalent day-length in the opposite wing of the year. The day in each square is equal in day-length to the day in the same row in the equivalent numbered column on the opposite wing of the year.
For example, looking along Row 17 you will find March 6th in column 15 in the ascending limb of the year. You will see that it matches October 6th also in column 15 (as you might expect) in the same row but in the descending limb of the year. You have matched up two dates with the same day-length. You can do the same for every day of the year, knowing that these paired days are matched but opposite so far as your endocrine and metabolic state is concerned, all other things being equal.
The calendar best fits people in latitudes of between 34 and 60 degrees. The seasons of course are reversed in the southern hemisphere.
© Julian Barker 2020