Sunday, December 9, 2018

Dark Days in the Northern Hemisphere: Tenth Anniversary Edition

This post originally appeared on this blog ten years ago today.  It is exactly as true now as it was then.


OK, this post goes out to all of you Northern Hemisphere dwellers who are affected by Seasonal Affective Disorder, or the winter blues, or who are just bummed out by finishing the day's work when it's already dark outside.


For tonight's sunset -- Sunday's, that is -- will be the earliest of the year. If tomorrow, as you leave your office or classroom or factory or whatever it may be, or as you glance up after a long day of righteous labor in the home, if it seems just a tiny bit brighter than it was today -- that's 'cause it is.

But isn't the solstice still like eleven days away?

Yes, it is. But the solstice, although it is the shortest day of the year, does not have the earliest sunset or the latest sunrise. The earliest sunset comes today, and then starts creeping later. By the 21st, the sunset is getting later exactly as fast as the sunrise is getting later, and thereafter starts to outpace it. By about January 3rd, the sunrise starts creeping earlier too, and before you know it it's spring.

But Why?

It's really hard to explain. It has to do with the fact that the Earth moves faster through the arc of its orbit this time of year, when it's closer to the sun, giving the cycle of day and night a little push forward. The pattern is reversed in June and July, when we are the furthest from the sun.

Can You Elaborate?

No. I can barely keep it straight in my own head, let alone articulate it clearly. You'll just have to roll with it.

[Photo taken via Google image from the Flickr site of someone named Alice Thelma, who presumably owns the copyright. I imagine it's the same Alice Thelma who had this blog of phenomenal Portland-at-night photos.]

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