Longest Night

[ato2]

Heard a couple of people rambling on about the shortest day, Southern Hemisphere in 2014, which is today. But, which is the longest night? Last night or tonight?
I figure it is tonight- the night of 21st- 22nd June, 2014.
The difference can only be a few seconds.
Anyone want to do the exact calculations? And, practically, how could anyone notice the difference?

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[Rwood]

According to a World Clock site, at Wellington both the 21st and 22nd are the same to within a second: 9h 11m 30sec of astronomical daylight, so I think the longest night would be between these 2 dates - but the table doesn't give sunrise and sunset to seconds-accuracy, so I can't confirm that. It can't be inferred directly from just the day-durations because the solar noon time changes slowly from day to day and this affects the outcome.

[intrepid]

Well, last night was the longest night for me...I read late and woke up late...!

Must be time for breakfast...well, my first one anyway!

[ato2]

Enjoy the breakfast, mate!

[ato2]

I got a ring from Fairfax to explain which night was the longest- they wanted it explained in ten words or less, I think!
In the end I emailed the journo a brief explanation, suitable for general readership. All he had to do was copy what I wrote.
And yet-surprise- he quoted me as saying something which was a little ambiguous! And put it on the front page under a large photo.
Ain't it the way!

[Rwood]

Longest night for me, too - slept in a bit! Good after a trying week at work.

I was able to do some calculations as World Clock gives day lengths down to seconds accuracy and my comment about zenith times doesn't affect length comparisons for adjacent or nearby days after all - though it does mean that the length of a day plus the following night is currently about 24hours plus 13 seconds (at Xmas it is plus 30 seconds!). Last night was our longest night - at Wellington astronomically speaking it was 14h 12m 43s.

At latitudes very close to the equator "equation of time" effects dominate the small day length changes due to latitude. For Quito (0 deg 15 min S) the December solstice days are longest (12h 08m 18s) but the shortest days are in mid-April (12h 06m 17s) and late August (12h 06m 16 sec) while around the June solstice the value is 12h 06m 32s. Nobody would notice this of course unless doing astronomy work perhaps.

Pontianak, Indonesia is virtually on the Equator: maximum 12h 07m 35s at December solstice, 2 minima of about 12h 06m 29s in late March and 12h 06m 27s in mid-September; 12h 07m 15s at the June solstice.

[ato2]

Thanks, Rupert.