h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I know that the earth 'wobbles' a bit as it rotates around the sun. Does anyone have any information about how this affects the earth's axis?

See, in my neck of the woods it used to be that the shortest day of the year (the winter solstice) the time between sunrise and sunset would be six hours, give or take a few minutes.

Today, with another three weeks to go until the solstice, the time between sunrise and sunset is already down to 5 hours 46 minutes, which makes me wonder how much shorter than usual the shortest day will be.

Also, if someone knows where to find statitiscs of solstice daylight hours - I'd like to make sure my memory isn't wonky.

The "wobble" is technically known as precession. It doesn't affect the length of the day in any way. It just affects where the sun is against the background of stars at the equinox. Over a period of 26,500 years, the earth's axis does one complete wobble, tracing out two cones.

I think if the day is as short as you say, then it always was and always will be. Norton's Star Atlas which I have at home, gives the times of sunrise and sunset for each day of the year for different latitudes.

I'm not really sure precession counts as a wobble.

There is the Chandler Wobble

http://www.daviddarling.info/encyclopedia/C/Chandler_wobble.html

but I don't think that's significant enough to have any noticeable effects on day lengths.

Precession is not really a wobble, but it is always described as such.

Yeah I thought about the precision first but thought it was on such a ludicrous timescale in relation to the question that I thought that wasn't really the issue. Not that my answer helps much either.

I think that there are quite a few wobbles that occur other than the precession due to external influences by other heavenly bodies but I haven't been able to find anything other than the Chandler wobble online.

Ah here's some stuff http://www.space.com/scienceastronomy/planetearth/earth_wobble_010131.html

Still doesn't really help the original question though

AH, I didn't know about that particular wobble. But it wouldn't affect the length of the day, except by milliseconds.