Shortest day of the year? Apparently not

Wednesday was the solstice – the summer solstice in the UK, no doubt with “Druids” and others at Stonehenge; the winter solstice in Australia, with its promise of the end of darkness. Or was it?

I started looking at this when I got myself so fascinated with 12-6-12, although I realise that you, my readers, were not.

The solstice is an astronomical event that happens twice each year as “the Sun reaches its highest or lowest excursion relative to the celestial equator on the celestial sphere”. What that means is that on the solstice the Sun appears to have reached its highest or lowest annual altitude in the sky above the horizon at local solar noon, which is not always 12:00 on the clock, particularly taking into account daylight savings or summertime.

The Northern solstice, in June, is the Winter Solstice in the southern hemisphere and the Summer Solstice in the northern hemisphere!

The dates given for June Solstice are close to what I expect: 20 June, actually at 23:09 GMT or UT (09:09 Sydney time on 21 June). And the Southern Solstice will be on 22 December at 11 am GMT or 22:00 in Sydney.

The trouble comes when you then equate that with the shortest or longest days, which we do. I heard it everywhere on Wednesday. But, according to the world clock sites I consulted, the shortest day in Sydney was not yesterday, 21 June, but last Saturday, 16 June. And, the longest day in Bournemouth (closest I could get to London for some reason) was Sunday, 17 June.

So, it looks like habit has taken over from scientific observation in this oh-so-scientific age. The solstices are expected to be on 21 June or December, even though they can be between 20 and 22 June or December. And, the Solstice is assumed to be the same as the shortest/longest day, even though it isn’t. We are slaves to superstition and belief about something that is easily measured and accurately predicted. There’s an irony!

So when are the other dates for 2012?
Bournemouth – Autumn equinox: 25 September; Shortest day: 21 December, the day before the Solstice.
Sydney – Spring equinox: 18 September; Longest day: 17 December, 5 days before the Solstice.

Of course, what this also may mean is that our thoughts on seasons and magical dates derive from the development of our society in the Northern Hemisphere and they don’t really fit into the Southern hemisphere.

Anyway, here’s some references if you want to look up more. Enjoy!


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