If one were to go to a fixed spot every morning and watch the sun rise beyond a horizon full of distinctive features, such as distant mountains and valleys, it would soon become obvious that the rising position moves along the horizon day by day. During the months of January to May, the daily change is northward, becoming noticeably smaller in early June and finally almost imperceptible, until it comes to stop on or very close to June 21. After this, the motion is southward once again, at first imperceptible, but gradually hastening until by August the change is almost a whole solar diameter each day. By the end of November, the daily progress noticeably slows once again, until the southerly limit is reached on or about December

21. Exactly the same pattern would emerge if one were to watch sunsets rather than sunrises. The dates when the limits are reached, June 21 and December 21, are known as the solstices.

In a location north of the tropics, the farther north the sun rises and sets, the higher it climbs in the sky during the day. The June solstice occurs, as a consequence, in summer. Thus in the northern hemisphere, June 21 is generally known as the summer solstice and December 21 as the winter solstice. In the southern hemisphere the converse is true. However, as this can cause confusion, especially within the tropics, the terms June solstice and December solstice are sometimes preferable.

Outside the polar regions, the summer solstice also represents the longest day and shortest night (technically, this may actually occur a couple of days before or afterward, but the difference is negligible). The winter solstice represents the shortest day and longest night. Within the tropics, though, this makes little difference—as one approaches the equator all days in the year come to have the same length.

The solstices are widely recognized culturally. Historically, summer and winter solstice festivals are documented the world over. The winter solstice in particular is a time of death and renewal, a time when, for many human communities, the sun must be halted in its southward (or northward in the southern hemisphere) progress and brought back—for example, by shaman-istic intervention—to enable a new growing season. The indigenous Chu-mash of California were just one of many peoples who held a major ceremony at this time because they believed human intervention to be necessary in order to maintain the delicate balance of nature. Similar principles may well have motivated a variety of rituals and ceremonies held at and around the time of winter solstice, such as the Hawaiian makahiki and the Incaic Inti Raymi. Pagan solstice festivals underlie the timing of the Christian festivals of the feast of St. John and Christmas.

See also:

Christianization of "Pagan" Festivals; Solstitial Alignments; Solstitial Directions.

Cusco Sun Pillars; Hawaiian Calendar.

Obliquity of the Ecliptic.

References and further reading

Krupp, Edwin C. Skywatchers, Shamans and Kings. New York: Wiley, 1997.

Ruggles, Clive, ed. Archaeoastronomy in the 1990s. Loughborough, UK: Group D Publications, 1993.

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