There is no physical "pole shift." (Update: There is still no physical "pole shift.")

I'd been planning on precisely and directly measuring the current location of the earth's axis of rotation, the north celestial pole, for a few days but had to wait for the weather to improve. I finally got my chance last night. Here are the results.

I used an 8" SCT telescope, aimed it at the north celestial pole, shut the tracking system off, and then ran an exposure for about 20 minutes. This produced the familiar circular "star trails" photo one gets when doing a long exposure while aimed at a celestial pole, but at a much higher angular resolution than you could get with a regular camera lens. In fact, it was so high in resolution that Polaris wasn't even in the same field of view, the only stars present were far too dim to be seen by eye and were all within about 30 arcminutes of the north celestial pole.

I measured from the star USNO-A2 1725-00691811. Its J2000 coordinates are:
21h 23m 00.84s +89d 52' 49.8"
Precessed to 2011.02 (last night), the coordinates would have been:
19h 30m 19.50s +89d 55' 05.8"
Therefore the star should have been 294.2 arcseconds from the north celestial pole.

My camera and telescope combination produce an angular resolution of 1.88 arcseconds per pixel when the images are scaled down to 1024 resolution:
[link to flickr.com]
I measured USNO-A2 1725-00691811 to be 156.9 pixels from the NCP in the image I took last night:
[link to i319.photobucket.com]
Original image here:
[link to i319.photobucket.com]
That corresponds to a distance of 294.972 arcseconds from the NCP, less than an arcsecond from the expected value and well within the resolution of the image itself.

There is only one possible conclusion; the north celestial pole and axis of the earth's rotation is right where it should be to within an arcsecond of its expected value. Precession and milliarcsecond scale shifts due to things like earthquakes and the Chandler wobble notwithstanding, there is no "physical pole shift."

Last Edited by Astromut on 01/11/2012 02:45 AM