Winter circles

 Polaris (Alpha Ursae Minoris) is known as the "Pole Star" or "North Star" because it is the nearest naked-eye star to the North Celestial Pole (NCP).  Under casual observation it appears to be motionless while the night sky rotates counter-clockwise around it.

E-M5iii + Leica 15mm f/1.7, live composite mode.

Close examination reveals that it is not quite at the center of rotation.  Polaris is currently 0.63° from the NCP. This is about 1.25 times the width of the full moon.  This distance is slowly changing because of precession of the earth's axis of rotation.  One hundred years ago the separation was 1.1°, and in 1776 it was 1.9°.  According to Belgian astronomer Jean Meeus the closest approach will occur on 24 March 2100, when the NCP will pass within 0.45° of Polaris, just slightly smaller than the width of the full moon.  Mark your calendars!

Polaris has significance beyond just being a navigational aid.  It is also the closest (430 ly) and brightest (mag 2.0) Cepheid variable star.  The brightness variations are too small (about 0.1 mag) to be noticed visually.  Polaris is close enough that its distance has been measured by parallax. This provides an important calibration point for the luminosity versus period relationship of Cepheid variables, which are used to determine the distance scale of the local universe (< 20 Million ly).

In addition to being a variable star, Polaris is also a multiple star, part of a three-star system: Aa, Ab, and B.  One of the companion stars (B) can be seen in small telescopes.  It is a magnitude 9.1 star at a separation of 18".  I have spotted it in a 60mm telescope, but have been unsuccessful with a 50mm scope.  The other companion (Ab) orbits too closely to be resolved easily and was first detected spectroscopically.  It was resolved photographically by the Hubble Space Telescope in 2006.

E-M5iii + Leica 15mm f/1.7 + softon filter.  ISO 1600, 60s.

There are several ways to find Polaris if you are unfamiliar with the night sky.  A magnetic compass will point toward the magnetic north pole, which is currently 8.4° east of true north when measured from Creede.  This is illustrated in the next picture, where I have added an outline of the Little Dipper and two white circles. The circle that intersects Polaris marks the location of the North Celestial Pole.  The circle to the right is the direction that will be indicated by a magnetic compass: 8.4° to the right (east) of the NCP.

Most people are familiar with the asterism known as the Big Dipper, which is part of the larger constellation Ursa Major.  The extension of a line between the two bright stars at the end of the "dipper" will point very close to Polaris.  I have added a line between these two stars (Alpha and Beta Ursae Majoris, aka Dubhe and Merak) in the above image.  Unfortunately, at this time of year (early December) the Big Dipper is skimming the northern horizon in the early evening and is largely obscured by mountain ridges.

 The above images show a yellowish glow along  the northern horizon.  This is what remains after color balancing the night sky.  The original daylight balanced image looks like this:

 I do not know if this pinkish glow is airglow or auroral glow.  It may be a combination of both.  It is not perceivable by eye, but is easily revealed in a long exposure (30-60 s) photograph.  The sky brightness at this time was sqml=21.09, which is considerably brighter than a "normal" dark sky in Creede.  The sun has been very active recently, and reports of auroral activity farther north are very common.  A Hydrogen-alpha image of the sun earlier the same day shows many spectacular prominences along the sun's limb.

Lunt LS50THa double stacked + ZWO ASI178mm camera.  Processed from a stack of 66 video frames.

As usual, click on any image to get access to the full-size version.