It officially began at 8:32 Pacific Daylight Time Sunday which was June 20th and also Father’s Day. That’s what is known as the Summer Solstice and the beginning of astronomical summer. 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.
The Summer Solstice is when the concentrated solar rays have moved to their farthest point to the north producing the longest day of the year. As the summer progresses those rays migrate southward reaching the southernmost concentration on the Winter Solstice (December 21/22) which is the shortest day of the year.
In between the Summer Solstice and the Winter Solstice are the Vernal or Spring Equinox and the Autumnal or Autumn Equinox. The equinox is defined by the National Weather Service as “the time when the sun crosses the earth’s equator, making night and day of approximately equal length over all the earth and occurring about March 21 (the spring or vernal equinox) and September 22 (autumnal equinox).
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.”
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