It’s that time of the year once again. I can’t tell you how many times I have said that. This time it has to do with the change of seasons. After another record setting summer of heat, wildfires and smoke we arrive at the end of summer.
That means its Autumnal Equinox time marking the end of astronomical summer and the official beginning of Autumn more commonly called Fall. Why is that so important? We have markers that let us know when the seasons have actually changed. Remember back in your first general science class in school how it was explained.
We know that the earth revolves around the sun in an elliptical orbit around the sun. Two things determine the seasons of the year: the position of the sun in it’s orbit around the sun and the angle at which the sun’s rays strike the earth. The sun’s rays would be spread evenly over the earth if it weren’t for the fact that the earth is tilted 23.5 degrees from the plane of the ecliptic. That angle allows the sun’s rays to be concentrated in the northern hemisphere in the summer and in the southern hemisphere in the winter.
This year the Autumnal Equinox occurs at 12:20 pm PDT on Wednesday September 22nd. According to britannica.com “Autumnal Equinox, two moments in the year when the Sun is exactly above the Equator and day and night are of equal length; also, either of the two points in the sky where the ecliptic (the Sun’s annual pathway) and the celestial equator intersect. In the Northern Hemisphere the the equinox falls about September 22 or 23, as the sun crosses the celestial equator going south. In the Southern Hemisphere the equinox occurs on March 20 or 21, when the Sun moves north across the celestial equator.”
In between the the Autumnal and Vernal Equinoxes are the Summer Solstice and the Winter Solstice. According to buyju’s,.com “The summer solstice, also known as estival solstice or midsummer, occurs when one of the Earth’s poles (North pole) has its maximum tilt toward the Sun (June 20-22). The winter solstice, or hibernal solstice occurs when one of the Earth’s poles (North pole) has it’s maximum tilt away from the Sun (December 21-22).”
The arranged stones at Stonehenge in England have long been thought to have been built to honor the solstice. In an interview for an article in the Register (England) by Brid-Aine Parnelli it was explained that archeological teams from universities of Sheffield, Manchester, Southampton, Bournemouth, and University College London have been investigating Stonehenge for ten years. They feel the monument was built as a symbol of a complex farm-subsidy agreement. A statement by the scientists states that they think the spot already had significance to the people there and building the monument made it even more important. “The solstice-aligned avenue sits on a series of natural landforms that, by chance, form an axis between the directions of midsummer sunrise and midwinter sunset” according to the scientists. Professor Mike Parker Pearson from Sheffield University, interviewed in the article, said “This might explain why there are eight monuments in the Stonehenge area with solistitial alignments, a number unmatched anywhere else. Perhaps they saw this place as the centre of the world.”
Let me know what you would like me to talk about or explain. You can comment below or email me at: [email protected].