Kemo D. (kemo_d7) wrote,
Kemo D.

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Kemo's Church


Good Morning and Welcome to another edition
! Ancient humans could not understand the real reason for the passing seasons. They associated what they observed with all sorts of mystical goings on. Today we’re going to explain the natural seasons. Now, when a theist tries to tell you about the "reason for the season," you'll know better! 

As astronomers reckon time, it happened over four and one-half eons ago. A cloud of cosmic proportions, composed of the dust and gases left over from the wreckage of early stars, condensed and coalesced to form a new star, with its retinue of planets, moons, and comets. That star was our sun, and one of those planets was the earth.

As might be expected from a knowledge of its chaotic origin, the solar system that resulted from this reassembly of stardust intermixed with primal matter fell somewhat short of geometric perfection. When all the forces that shaped the early earth had been resolved, they left it spinning on an axis tilted 23.5 degrees away from the perpendicular. 

Although the points in space to which the north and south poles of that axis aim change slowly over a period of 26,000 years, Earth's orientation in space remains essentially unchanged as it completes any particular revolution about the sun. 

This means that as the earth orbits the sun (see Figure 1), there is a point where its north axial pole is tilted maximally toward the sun (around June 21) and a point where that pole is tilted maximally away from the sun (around December 21). There are also two points in the earth's path (around March 21 and September 23) where the axis is aimed neither toward nor away from the sun.


Figure 1 


When the North Pole is inclined toward the sun, the Northern Hemisphere experiences the warmth of summer. At the same time, however, the Southern Hemisphere feels the chilling winds of winter, since its pole is tilted away from the sun. Northern winter occurs when the Northern Hemisphere faces away from the sun, and less of its surface is warmed by solar rays. The seasons of spring and autumn occur when the two poles are angled neither toward nor away from the sun.

Toward the end of the last Ice Age, people living in the Northern Hemisphere began to notice that at
midday in summer the sun appeared to soar high above the southern horizon. In winter, it barely rose above the horizon. It was noted also that in the summer the days were longer, whereas nights were longer in the winter. How to account for these facts? Since the ancient watchers of the skies knew nothing of the sphericity of the earth - let alone that it spun on an axis out of plumb with the plane of its orbit - they developed mythological explanations. The sun was a god. After all, it appeared to move across the sky every day. Everyone "knew" that movement was the hallmark of life. The sun was alive - divinely alive.


When the sun was high in the midday sky, the "god" was healthy and vivifying. When the solar disk sank to its lowest point in the year (when the earth's north axial pole was tilted maximally away from the sun), its feeble rays could scarcely scatter winter's chill at midday: the god was dying. For a short while, the sun (sol in Latin) appeared to stand still (stitium, in Latin) before "reviving" and starting on its journey back north.


And so this shortest day of the northern year (often falling on December 25 in the old Julian calendar, and on December 21 in our Gregorian calendar) was named the winter solstice. Six months later, on the longest day of the northern year, the sun once again appeared to stand still - now at its highest altitude in the midday sky - and that event was named the summer solstice.

Midway between the winter and summer solstices, about March 21 and September 23, the length of the day equalled that of the night. These points in the calendar were termed the vernal (spring) and autumnal equinoxes (from the Latin æquinoctium, equality between day and night). For the ancients, these dates were the occasion for fertility and harvest festivals, respectively.

We now know that the solstices and equinoxes alike are an inheritance from the confusion in the natal nebula that engendered our earth and its siblings. Because the earth's axis is permanently bent away from the perpendicular, the lengths of day and night (except at the equator) change continuously as the planet moves in its orbit.


At the winter solstice (see Figure 2-A) when the north pole is tipped 23.5 degrees away from the sun, an observer moving along with the Northern Hemisphere will spend more time in darkness than in light - for the simple reason that less than half of the Northern Hemisphere is illuminated. At the equinoxes (see Figure 2-B), when the earth's axes are tilted neither toward nor away from the sun, observers all over the planet spend the same amount of time in darkness and in daylight.

Figure 2-A and 2-B

Even though the solstices and equinoxes do not mark the motions of a god traveling across the heavens, they do mark the progress of the space-ship we call Earth in its passage through the void. They note the natural pulse of life as it has been evolved, sustained, and carried along the same celestial path for time out of mind.


As we pass these four milestones on our annual journey about the life-sustaining fusion-fires of the sun - the only star known that heats the blood of self-conscious beings - we reflect upon our astronomical uniqueness. We appear to be alone, in a universe devoid of plan or purpose. There is no cosmic intelligence that counts how many rides we complete on the merry-go-round whose axle is the sun. Only we can do the counting. We only have each other.


For this reason, it is the custom for many as they mark the passage of the solstices and equinoxes to pause for celebration: to celebrate and cherish their fellow travelers, to celebrate the wondrous fact that they are part of the human species - the only species known that can understand and appreciate the implausibility of its own existence.

Kemo D. (a.k.a. no.7) 

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