Navigator’s Companion

September 21, 2013

Polaris_half (3)

Photographer: Greg Parker
Summary Author: Greg Parker

Polaris is the brightest star in Ursa Minor or the Little Bear. It’s also often referred to as the Pole Star, the North Star, or the Guiding Star. It's the only relatively bright star (magnitude of 1.98) near either of the celestial poles. Currently only 0.7 degrees away from the north celestial pole (shown in green cross-hairs at a 2 o'clock position), Polaris is thus used in both navigation and in setting up equatorial mounts for astronomical imaging. It’s been used for navigation since antiquity.

Polaris is a multiple star system with two smaller companions, and two more distant companions. It’s also a Cepheid variable, lying at a distance of 434 light-years. There are many "faint fuzzies" (galaxies) in the background of this image. All of them appear closer to the north celestial pole than Polarissima Borealis (NGC 3172), a bright, spiral galaxy within 1 degree of the pole, but off the frame here.

This image was taken using the mini-WASP parallel imaging array at the New Forest Observatory and subsequently processed by Noel Carboni in Florida. Anyone who has imaged near the Pole Star using a German Equatorial Mount (GEM) knows it’s very difficult work, as the pole presents a coordinate singularity. This makes guiding and tracking extremely challenging.