Sunday, December 21, 2014

Happy Winter Solstice

I'm posting this on Dec. 21, 2014, which is often considered as the Winter Solstice, the shortest day of the year for Northern Hemisphere.

Now most people will associate that with the idea that from this day onwards, sunrise will be earlier and sunset will be later in the day. However, this article shows that that is not the case as they showed in the table.

Day Sunrise Sunset Day length
(All times GMT)

Turns out, it has to do with a day not being exactly of the same length all year long.

There are two reasons why the length of the solar day varies, the first being the fact that the axis of the Earth's rotation is tilted - 23.5 degrees from vertical - and second, the Earth's speed varies because it moves in an elliptical orbit around the sun, accelerating when it is closer to the star's gravitational pull and decelerating when it is further away.

The sun therefore in effect lags behind the clock for part of the year, then speeds ahead of it for another.

So there you go!

11 December 2014 07:56 15:51 7:55:37
21 December 2014 08:04 15:53 7:49:45
31 December 2014 08:06 16:01 7:54:39
31 January 2015 07:41 16:48 9:06:42

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