Yesterday’s Thoughts

June 23, 2005

Seasons

Much celebration of the Solstice on Tuesday. Summer is here.

Two problems:

For those of us on in the Pacific time zone and west to the date line, the Solstice was on Monday.

According to the U.S. Naval Observatory the solstice occurred on June 21 at 06:46 Universal. In Pacific Daylight Time that was 23:46 on June 20. I wish I had been paying attention at the time.

Problem two:

Can anyone explain to me how the seasons are delineated? More importantly, when did the span of the seasons move 1/8 of a year back. To Shakespeare Midsummer was June 21, but I was taught in school, and it seems to be widely accepted that summer starts on or around June 21.

The problem that I have as a life-long resident of the temperate climes, and Northern hemispheres, is that it doesn’t make any linguistic sense for December 19th to be fall and March 19th to be called winter. December 19th has much more in common with other winter days than it does with fall days.
December 19th has approximately the same length of day as December 23. The day on March 19th has much more light. The temperature on December 19th is likely to be close to the lowest of the year (winter) while on March 19th the temperature will be distinctly mild in comparison. The commonsense definition would put December 19th in the winter and March 19th in the spring.

I don’t really find any definitive statement that astronomers define the seasons at all. This page at Science World talks about the reasons for seasons, but gets side tracked in the rebutting the notion that the reason for seasons is that the Earth is closer or farther from the sun, and doesn’t cover why summer is thought to start on the solstice. If you follow the links from the season page to summer, fall, winter and spring, you will see that they are all defined as starting at their respective events of the sun cycle. This is an implicit statement about the seasons.

I would think that there would have been some astronomy convention (in both senses, arbitrary and political) that stated that the seasons ran from equinox to solstice and solstice to equinox.

(I don’t want to knock Science World’s site. It is great. Everything that I have looked at is very clear and interesting written. Recommended.)

I’m apparently not the only person who has a problem with this definition. Over at the Bad Astronomy site, Phil Plait, opines along the same lines as I have, although he is an astronomer, and presumably knows more about the subject than I do.

Phil adds to the argument that other modern cultures do consider the solstices mid-points of the warm and cold season. Japan is one example

The changes of seasons are the cross-quarter days and these have an ancient history. There were pagan holidays for all of these celebrated in Europe. Three of the cross-quarter days correspond to or have evolved into well known holidays: May Day, Halloween, Ground Hog Day. The early August cross-quarter day is Lammas.

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