EYES TO THE SKY: Star wheels, key to constellations; best-of-year meteor shower |

Here’s one way to see the constellation Gemini. The two bright stars Castor and Pollux each mark a starry eye of a Twin. Image courtesy EarthSky.org

December 11 – 24, 2017

Photo courtesy EarthSky.org

Mount Washington — All the world would have us believe that electronic devices are indispensable for the stargazer, but I’m compelled to share with you my enduring enthusiasm for my paper star wheel, or planisphere, a stargazer’s basic field guide to the night sky. Especially now, during the season of gift-giving, here’s a gift for all ages that encourages contact with nature and, at that, during the nighttime hours when most are drawn indoors. The concept of a planisphere – a chart of the sphere of the sky drawn for viewing in two dimensions – originated centuries ago; its hands-on format makes it an exciting introduction to the night sky.

I reach for my star wheel in preparation for stargazing: to orient myself to stars and star patterns to expect at my location before I go outdoors. Popular planispheres are constructed of light cardboard about 10 inches square and consist of a moveable chart within a frame: Prominent constellations are drawn on an inner circle that is rimmed with a band on which all the dates of the year are inscribed. The simple frame displays the constellations in a broad oval opening around which the cardinal directions are noted. I grasp the rim of the moveable inner circle and turn it to match the desired date and time. I study the star patterns to be reminded of when stars are rising above the eastern horizon and setting in a westerly direction. In addition, I’ve customized my chart by creating a quick reference for stellar magnitude. I taped two strips of paper, one on either side of the frame so as not to cover the opening. In descending order from greatest to lesser magnitude, I’ve written 14 of the brightest stars. On one side are Sirius to Betelgeuse while, on the other, Altair to Regulus.

The view shown here is for 2 a.m. Thursday morning, Dec. 14, when the radiant will be high in the southwestern sky near the zenith. Image courtesy Sky & Telescope

Like many astronomy buffs, I also own planetarium software. Starry Night Pro and Starry Night Enthusiast 7 are available for purchase. Stellarium, a free program, is similar. Please see the Resources section for more information on planispheres, including how to make your own, and all manner of both high-tech and low-tech devices for stargazing. Add a reflective vest to your tool kit for use when walking on roadways. If you need light to see by, use red so as not to interfere with your night vision. For optimum viewing, allow your eyes to adjust to the dark for about 20 minutes.

Celestial Viewing Highlight:

Sunrise 7:13 a.m.–7:15 a.m. Astronomical twilight
ends 5:32 a.m.–5:34 a.m. Most likely to see Geminid meteors before 5:30 a.m. Image courtesy of Sky & Telescope

Heads up for the Geminid meteor showers tonight through the 16^th.
Peak predicted at 2 a.m. on the 14^th. Look especially from 10 p.m. the 13^th through dawn the 14^th.
Learn more at https://www.skyandtelescope.com/observing/geminid-shower-2017/