In message . com, Phil
Meades writes
With the Winter Solstice occuring at 0:22 UT on 22/12/2006 this leaves
me a bit uncertain as to which is the shortest day this year. Is it the
21st or the 22nd?

I used Cartes du Ciel and SkyMap 11 to try to work out which was the
shorter. Cartes du Ciel seems unable to distinguish between the length
of the two dates. SkyMap 11 indicates that the 22nd has 1 second less
daylight and is thus the shortest day. Is this correct?

This also raises the question of what set of circumstances would result
in both days either side of the solstice being of equal length so that
we had two shortest days - to an accuracy of one second.

Cheers - Merry Christmas
Phil Meades


2007-12-22 06:12 is the solstice according to

http://www.hermetic.ch/cal_sw/ve/ve.htm

But for length of day it looks like a dead heat for 21st and 22nd for
Edinburgh - two shortest days !

http://www.timeanddate.com/worldclock/astronomy.html

Length of day
Date Sunrise Sunset This day Difference

21 Dec 2006 08:42 15:40 6h 57m 29s - 0m 08s
22 Dec 2006 08:43 15:40 6h 57m 29s - 0m 00s

For a different longitude 6 hours further west , 21st is shorter
since the solstice occurs on the 21st

Brian
--
Brian Howie