Dipper stars, and Polaris becoming "more north"!

Event Date: January 4th

Time: 10:00 PM

Brief

   I showed the Big Dipper yesterday with only the stick figure.  Today, I will take away the stick figure and only put the star names.  Besides that, we have the Little Dipper showing, representing the body and tail of Ursa Minor.  The end of the little bear's tail, is Polaris, which is honored to be the "North Star".  It is only about 40 arc-minutes from the north celestial pole, and getting gradually closer to it by a few arc-minutes. By the start of the next century however, Earth's precession will bring the star away from the axis and years later, the only stars closer to it will be much dimmer.

   Here are the two Dippers with stars only and the celestial grid.  Notice how close Polaris is to the north celestial pole now.  The second image is a field of 1.4º, indicating that the star barely fits in the field, yet fitting a little moreso each year; good for polar alignments with equatorial telescopes!

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp

Detailed

   Polaris is slightly closer than the last time I showed this field sometime last year.  At 40' 49" away from the pole, which I calculated by subtracting its 89º 19' 11" declination from 90º (0', 0"), a smaller field of view for an eyepiece can be used to get it and the north celestial pole into view.  Granted, a person should know the star patterns on and near the pole for the best alignment, if/when necessary. For telescopes that track in equatorial for use of long-exposure photos, having proper polar alignment can help tracking; as a result little to no drift at all over so many hours.  For those using alt/az telescopes, for which long-exposure photography is much less common, near-perfect alignment is not so necessary.

    Getting back to the Dippers, watch as the dimmer little one gradually moves in the sky over the course of the long, winter nights.  If you are able to stay awake between Sunset to Sunrise and haved nothing better to do on a clear night but view, perhaps you can notice the very gradual movement of the stars.  It may sould dull, yet can give a good appreciation of our rotation on Earth, and how slowly we really do move in relation to the stars: 23 hours and about 56 minutes for a sidereal day.