Sky at a Glance December 21 – 28

Photo showing the constellation Orion with surrounding stars in constellations making up the Winter Hexagon.

This Week’s Sky at a Glance, 2019 December 21 – 28 ~by Curt Nason

Having official constellations doesn’t prevent us from imagining our own. The sight of Orion, with club raised high and a lion-skin shield warding off the horns of a raging bull, has been etched in my memory for over half a century. But, come December, reddish Betelgeuse in Orion’s armpit becomes Santa’s red nose in profile, the curve of the shield outlines a sack of toys, and the iconic three-star belt is…well, Santa’s wide black leather belt. And on cold, clear nights there is no mistaking that twinkle in his eye. Look to the north and there is Santa’s sleigh, usually seen as the Big Dipper, being loaded up for the long night’s ride.

Many doors and windows are decorated with wreaths and the window of the winter sky is no exception. Here, Betelgeuse is a red light near the middle of a wreath we call the Winter Circle or Hexagon. By mid-evening you can trace the lights decorating the wreath, from blue-white Rigel in Orion’s leg to brilliant Sirius the Dog Star, up through Procyon the Little Dog Star, around Pollux and Castor in Gemini and Capella in Auriga to orange Aldebaran as the Bull’s eye, and back to Rigel. Imagination is a gift and Santa won’t mind if you open yours before Christmas.

This Week in the Solar System

Saturday’s sunrise in Moncton is at 7:58 am and sunset will occur at 4:36 pm, giving 8 hours, 38 minutes of daylight (8:00 am and 4:44 pm in Saint John). The Sun reaches its farthest southern position, over the Tropic of Capricorn, at 12:19 am on Sunday. In Moncton, both Saturday and Sunday have 8 hours, 37 minutes and 42 seconds of daylight, 5 second less than both Friday and Monday, and 7 hours, 8 minutes less than on the summer solstice. Next Saturday the Sun will rise at 8:00 am and set at 4:40 pm, giving 8 hours, 40 minutes of daylight (8:02 am and 4:48 pm in Saint John).

The Moon is new on Thursday, giving dark skies for observing faint star clusters and nebulae with new Christmas telescopes. For an observing challenge, use binoculars to see if you can spot the extremely thin crescent above the southeastern horizon before sunrise Wednesday morning. Mars will be about 15 degrees to its upper right. Saturn sets shortly after 6 pm Christmas Eve, followed by Venus about 70 minutes later. Jupiter is in conjunction with the Sun on Friday, and by late January it will have traded places with Mercury in the morning sky. A few shooting stars from the Ursid meteor shower might be spotted Sunday morning or evening, emanating from the bowl of the Little Dipper near the North Star. This is usually a minor shower but it has been surprisingly active on rare occasions.

Questions? Contact Curt Nason.

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