10 years ago when I left my office at 4:30 PM on Dec. 31 it was pitch dark. Now it's deep dusk. Why?

Question

I notice that at 4:30 PM on December 21 when I leave the office in Edmonton, Alberta it is no longer pitch dark as it was only a few years ago...only a deep dusk and not dark until almost 5 PM. That would mean the Northern Hemisphere is not as far away from the sun as it used to be on the winter solstice. Is there any evidence to back this up?

Answer 1

I am sorry for all the speculation but there is a web site:
http://www.divulgence.net/
That states that the Earth has recently shifted some 26 degrees.
But from the site :
http://en.wikipedia.org/wiki/Axial_tilt#Measurement
The Earth's axial tilt varies between 22.1° and 24.5° (but see below), with a 41,000-year period, and at present, the tilt is decreasing. In addition to this steady decrease, there are also much smaller short term (18.6 years) variations, known as nutation.

I trust the latter: I’d say the lighter skies have more to do with light pollution.

Answer 2

There is no evidence to support the idea that the Earth's axial tilt or orbit has changed at all in the past year.
There are small fluctuations in the axial tilt and Earth's orbit, but these would amount (at most) to a few milliseconds difference, not enough for us to notice.

The difference you notice could be due to different weather from last year.
For example, if last year it was a clear sky and this year there are clouds, those clouds will reflect the streetlights and other outdoor lighting in a city, making it appear brighter.

Answer 3

There has been significant urban growth in Edmonton in the last 10 years (indeed, in all cities in western Canada). The light you are seeing is not dusk, but is urban light pollution.

Answer 4

I have no idea...dark isn't until about 6:30 or 7:00 here in South Georgia

Answer 5

This was the first year for a change in Daylight savings time. Maybe that is the answer? I am only guessing, here. Or...cloud cover on a particular day makes it dark sooner.

Answer 6

additionally in case you pass to the area provided via Morningfoxnorth you notice moonrise replaced into at 1300 hours so the sky could have some easy in it, plus there continues to be at 1630 some civil twilight left

Answer 7

I dont know nuttin bout astronomy but my uneducated guess would be the status of the moon. It changes all the time. If the moon is out, duh, the sky is brighter.