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equinox,solstice.

Posted: Sat Dec 15, 2007 4:27 pm
by Allan
What is more seasonal than this topic :?:
I have been having my doubts about the equinoxes and solstices so I did a search. It appears that they are not fixed but are predictable. I think the summer solstice is always the same on 21st. June but haven't checked all possible dates. For the rest there are formulae and calculators, such as

http://stellafane.org/misc/equinox.html

There is also the little matter of the darkest morning and evening not being in step, that is quite adequately covered on the BBC weather website. Alternatively search "analemma"
Allan

Posted: Sat Dec 15, 2007 4:32 pm
by oldherbaceous
Dear Allan, thats rather interesting, i did not realise there was so much to it.

Posted: Sat Dec 15, 2007 6:03 pm
by John
Hello Allan
This is indeed a fascinating topic for those of us with an interest in what's happening up there. Winter Solstice on or about 21st Dec is the term most people have some idea of but 'perihelion' (when the earth's orbit brings us closest to the sun) isn't until Jan 3rd and is usually ignored. This site:

http://www.earthtools.org/

is very easy to use for finding your own twilight/sunrise/sunset times - just move the map to put the marker over your own patch and hey presto your own times are shown.

John

PS Looks like we'll miss the Geminid meteors this year because of this awful low cloud.