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"Pongáio" was the name my Aunt Mona gave to a long, green, cool room where we gathered at her home —
replete with comfy chairs, a rocker, sewing machine, sewing goods, beautiful beads, shelves, books, bibelots, photographs, odds'n'ends, mementos of a life, treasures —
a gathering of all the useful & 'useless' things that so make life a pleasure.



Saturday, March 20, 2010

Seasons

Today is the our Autumn Equinox, exact at 14:33.
The Earth will slowly slide into longer nights, shorter daylight.

This year I'm rather relieved at this, as we'll soon be having cooler weather.
Also, with the colder nights, "cold" for us that is, The Very Noisy Neighbors tend to quiet down, much to my relief.

When I read about the reasons for the having seasons here on Earth, many explanations say something like "the tilt of Earth's axis changes, thus receiving more or less sunlight in the southern or northern hemisphere". But that is rather falacious, implying that the Earth changes its tilt, that it "moves about", from an angle of 23°plus to one side of a "vertical axis", swinging to the 23°plus on the other side.
The axis does not change: it always "points" in the same direction. It is the Earth's movement on its orbit around the Sun that causes the effect of more sunlight in one hemisphere than the other.


Below, a very cool interactive site that lets you "play" with the perspective, the viewpoint, and the Earth's orbit, which makes it very easy to see the mechanics of the seasons:

This is an image of the flash site. 
Click HERE to go there: 
http://astro.unl.edu/naap/motion1/animations/seasons_ecliptic.swf

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