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Astro for December

“Uncle Bob”

Setting Up for Winter

After all the clouds of late fall have passed by, winter’s bright twinklers are bound to capture attention. This article looks ahead then to late December and the months of January and February. Our map was accessed from Sky Map Online – a site where you can designate the date and time for any location, and see the sky objects and their positions. You can also get a printed sheet, black on white, to hold overhead to orient yourself. If you are facing east, hold the edge marked E to the front, and likewise for other directions.

Our map above is for Haverhill, NH, January 10, 2018, at 20:30 hours (8:30 pm), but it should serve well for the northeastern U.S. for weeks before and after that date along with a slight time adjustment: look later in December and earlier in February. One feature at the turn of New Year is not a twinkler, but a fuzzy gray Andromeda Galaxy. You see it on the map just east of the Great Square of Pegasus and just above the printed title Andromeda (a faint M110). It has drifted a little west of the zenith overhead, but if you are out earlier than 8:30, look straight up for it. Andromeda is a galaxy much like our Milky Way and over 2 million light years distant, but it is predicted to merge with us in the very distant future – barring any travel ban.

The northerly stars can be accessed most of the year with some exceptions. The Big Dipper lies very low at the horizon in winter, while opposite the north star Polaris, Queen Cassiopeia and her king Cepheus ride high. Polaris is the highest up of the stars in Ursa Minor. The M-shaped Cassiopeia, a W shape in summer, will be about halfway from Polaris to the zenith.

On an evening drive in mid-November, I observed a twitchy twinkler to the north. I recognized it at once as Capella, the alpha star of Auriga – a pentagonal constellation that comes out of the northeast. Through the year it circles around Polaris toward the west – as indeed the whole sky does – and it settles below the horizon six months before the Dipper does. Auriga has three deep sky objects that you can access with any pair of binoculars or even your unaided eyes on dark nights. Hanging either side of its trailing, easterly, edge are three star clusters. Rather than millions, they are merely thousands of light years distant (are you remembering to turn the map?).

In the chilly nights of December one can get a further chill watching Taurus the Bull rise in the east. The center of this constellation is a V-shape lying on its side. This figure is known as the Hyades, and it contains the angry red eye of the Bull. This is the star Aldebaran.

Our Bull’s eye has another red rival. Betelgeuse is the star at the right shoulder of Orion, the most recognizable winter constellation. In saying “right” shoulder, I’m taking the percentage bet that the hunter is right-handed and facing us, with a dagger hanging from the right side of his belt of three bright stars. Many say that Betelgeuse will, sooner than most, explode in a supernova. At 310 light years from it, we may sense measurable effects when it does – or rather, 300+ years after it did.

Brighter than Betelgeuse is Rigel, the hunter’s left foot. Rigel is a multiple star and with a good telescope, you might see it’s dull blue companion. In the overall constellation there are many such multiple systems to explore. Two such areas are in the head and belt. The middle “star” of the dagger is actually the Orion Nebula, a star factory of gas and newborn bright stars. Trailing behind Orion’s right side and a little south is the brightest star we see after our own Sun. This is Sirius in Canis Major, the hunter’s faithful canine companion.

The map shows many other areas to explore. Following Orion in late winter will be the Gemini Twins and Leo the Lion. You can see them tonight if you go out past midnight. Why wait?

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Have I mentioned my memoir? It contains an entire chapter on my experiences in starry matters. It’s on sale at the Uncle Bob Store.

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