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- Nov 9, 2001
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Re: Picture this.
I don't think the Earths axis has shifted dramaticly over the past twenty years, but there are probably small effects caused by leap years that can mean that the sun is in different positions on the 21st of June.
There is quite a good site that explains changes in the Earths tilt here: http://www.doc.ic.ac.uk/~kpt/terraquest/va/ecology/ecology.html#B
Bill said:Now! on the longest day(21 june) over 20 years ago the Sun would set(ACCORDING TO MY HORIZON)just LEFT of the CHIMNEY opposite me.
Now!in 2004 the Sun set RIGHT OF THE SAME CHIMNEY and quit a way to!!!!!.
I have been observing this for years now every 21st June and it is a pitty i have not gotten all of this on film.
What do you make of that???
Bill.
I don't think the Earths axis has shifted dramaticly over the past twenty years, but there are probably small effects caused by leap years that can mean that the sun is in different positions on the 21st of June.
There is quite a good site that explains changes in the Earths tilt here: http://www.doc.ic.ac.uk/~kpt/terraquest/va/ecology/ecology.html#B
It is now believed that a cycle of three main irregularities, in the Earth's orbit are the main factors initiating an ice age. These are as follows:
The first irregularity is the tilt of the earth's axis from 22ƒ to 25ƒ which occurs in a cycle that repeats itself every 41,000 years. (A change in the earth's tilt changes the amount of heat from the sun that reaches the polar regions.)
The second irregularity is the orbital procession which completes its cycle every 21,000 years. This determines the season at which the earth is closest to the sun during its orbit. Currently the earth is further from the sun during the northern hemisphere's summer than in the winter.
The third cycle, with a period of 100,00 years, alters the shape of the earth's orbit, and its eccentricity amplifies or minimises the effect of the procession. This was first put forward in the 1870's by a Scottish amateur scientist, James Croll, and verified in the 1920's by a Serbian mathematician, Milutin Milankovitch. He showed that these variations were the basis for the significantly cooler summers every 21,000 and 41,000 years. These could help cause an ice age by beginning the build up of ice at the poles. The additional time it took for the icesheets to grow to their maximum sustainable size has been suggested as reason for the ice ages occurring every 100,000 years.