Sky at a Glance 2020 December 12 – 19

Photo depicting constellations view toward the northeast in early December.

This Week’s Sky at a Glance, 2020 December 12 – 19
~by Curt Nason

Evening stargazing can be tricky this time of year with all the festive lights, especially if you have a neighbourhood Griswald. If you happen to be out, try identifying a few constellations. In the northeast there is pentagonal Auriga the Charioteer, with bright Capella the Goat Star at one corner. To the right is the V-shaped face of Taurus the Bull, with the dipper-like star cluster of the Pleiades marking its shoulder. Orion and Gemini follow below Taurus and Auriga. Above Auriga is Perseus, seemingly standing on the bull’s back. It is here a patient stargazer can watch a marvel of the night sky.

In mythology, Perseus beheaded Medusa and used her snaky head to seek revenge on tormentors by turning them to stone. The second brightest star in the constellation Perseus represents the evil eye of Medusa and it is called Algol, the ghoul or demon. There is a reason for this name. Every three days, minus about three hours, this star slowly dims by a factor of three and regains brightness over several hours. Algol is an eclipsing binary, two stars orbiting each other closely and aligned to our line of sight. When the smaller, dimmer star passes in front of the brighter one we can see their combined-light diminish and recover. By comparing it with nearby stars of similar brightness you might notice Algol dimming and getting brighter. Our next convenient evening opportunity to watch this is on New Year’s Eve, when Algol is dimmest around 8 pm.

This Week in the Solar System

Saturday’s sunrise in Moncton is at 7:52 am and sunset will occur at 4:33 pm, giving 8 hours, 41 minutes of daylight (7:54 am and 4:41 pm in Saint John). Next Saturday the Sun will rise at 7:57 am and set at 4:35 pm, giving 8 hours, 38 minutes of daylight (7:59 am and 4:43 pm in Saint John).

The Moon is new on Monday and it makes a scenic pass below Jupiter and Saturn on Wednesday. Jupiter has moved to within one degree of Saturn, putting them within a low to medium magnification view of most telescopes as they move toward an exceptionally close conjunction on December 21. Mars remains close enough all month to offer views of its surface features in a telescope and high enough in early evening for higher magnification observing. Having crossed the constellation border into Libra in late November, Venus moves into Scorpius this week where it has a close conjunction with Graffias in the scorpion’s left claw on Friday morning. The reliable Geminid meteor shower peaks from Sunday evening to Monday morning. Moonlight will not be a problem but the weather could be a Meteor Grinch. Take advantage of any clearing from Friday evening to Tuesday morning and spend some time looking for shooting stars. Dress warmly and look up.

With astronomy meetings and outreach activities on hold, you can watch the local Sunday Night Astronomy Show at 8 pm and view archived shows.

Questions? Contact Curt Nason.

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