Stellar halo around Mirfak on December 17, 2022 at 6 p.m. (Chris Vaughan and Starry Night Education | SkyNews
Stellar halo around Mirfak on December 17, 2022 at 6 p.m. (Chris Vaughan and Starry Night Education)

This Week’s Sky: December 12-18

The Geminids meteor shower reaches its peak, Mirfak will sparkle in binoculars, and the Hyades will reach its highest point this month.

Every week, SkyNews publishes a list of key events in the Canadian sky in This Week’s Sky. This series gives you all the latest news in Solar System movements, including where the planets are in our sky and Moon phases. From eclipses to meteor showers, This Week’s Sky keeps you updated on the best in upcoming astronomical highlights.

Tuesday, December 13 – Geminids meteor shower peak (overnight)

Geminids meteor shower peak on December 13, 2022 at midnight. (Chris Vaughan and Starry Night Education | SkyNews
Geminids meteor shower peak on December 13, 2022 at midnight. (Chris Vaughan and Starry Night Education)

The Geminids meteor shower, usually one of the most spectacular showers of the year, runs from November 19 to December 24 annually. The number of meteors will gradually ramp up to a peak during the wee hours of December 14, and then decline rapidly on the following nights. 

Geminids meteors are often bright, intensely coloured, and slower-moving than average, because they are produced by sand-sized grains dropped by the asteroid designated 3200 Phaethon. 

In the Americas, expect to see the most Geminids beginning after dark on Tuesday evening, December 13, and continuing until dawn on Wednesday morning. True Geminids will appear to radiate from a position above the bright stars Castor and Pollux, but the meteors can appear anywhere in the sky. The years when the peak night sky is moonless, up to 120 meteors per hour are possible around 2 a.m. local time — the time when the sky overhead will be pointing toward the densest part of the debris field. 

In 2022, a waning gibbous Moon will rise in mid-evening, obscuring the fainter meteors.

Friday, December 16 – Third quarter Moon (at 08:56 GMT)

Third quarter Moon on December 16, 2022 at 08:56 GMT. (Chris Vaughan and Starry Night Education | SkyNews
Third quarter Moon on December 16, 2022 at 08:56 GMT. (Chris Vaughan and Starry Night Education)

The Moon will reach its third quarter phase on Friday, December 16 at 3:56 a.m. EST, 12:56 a.m. PST, or 08:56 GMT. The Moon will rise at about midnight local time, and then remain visible in the southern sky all morning. The last quarter Moon will be illuminated on its western side, towards the pre-dawn Sun. 

Last quarter Moons are positioned ahead of the Earth in our trip around the Sun. About three and a half hours later, Earth will occupy that same location in space. The week of moonless evening skies that follow the last quarter will be ideal for observing deep sky targets. 

Saturday, December 17 – Stellar halo around Mirfak (all night)

Stellar halo around Mirfak on December 17, 2022 at 6 p.m. (Chris Vaughan and Starry Night Education | SkyNews
Stellar halo around Mirfak on December 17, 2022 at 6 p.m. (Chris Vaughan and Starry Night Education)

During evenings in mid-December, the constellation of Perseus can be seen climbing the northeastern sky. For 2022, it will also be above Mars. Since Perseus is superimposed on the outer reaches of the Milky Way, it is filled with rich star clusters. The largest of those surrounds its brightest star, Mirfak, or Alpha Persei. 

Melotte 20, also known as the Alpha Persei Moving Group and the Perseus OB3 Association, is a collection of about 100 young, massive, hot B- and A-class stars sprinkled over several finger widths (or three degrees) of the sky. The cluster can be seen with unaided eyes, but it sparkles in binoculars (green circle). Its stars are approximately 600 light years from the Sun and are moving as a group — Mirfak along with them. That elderly yellow supergiant star has evolved out of its blue phase and is now fusing helium into carbon and oxygen in its core. 

Sunday, December 18 – The Hyades cluster (all night)

The Hyades cluster on December 18, 2022 at 8 p.m. (Chris Vaughan and Starry Night Education | SkyNews
The Hyades cluster on December 18, 2022 at 8 p.m. (Chris Vaughan and Starry Night Education)

Located only about 150 light years away from the Sun, Taurus’ triangular face is actually one of the nearest open star clusters to us. It is commonly called the Hyades, named for the five daughters of Atlas in Greek mythology. It also has the designations Melotte 25 and Caldwell 41. 

The cluster contains several hundred stars, with a half-dozen or so readily seen under moonless suburban skies, many as close pairs. It is a superb target to view in binoculars (green circle). The five brightest members, all naked-eye stars, are within a few light years of one another. The cluster’s stars likely formed together about 625 million years ago. 

The bright orange star Aldebaran, at the lower (southeastern) vertex of the Hyades, is actually not part of the cluster. It is less than half as far away! In mid-December, the Hyades will “climb” the eastern sky in the early evening and reach its highest point due south by 11 p.m. local time. 

Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through AstroGeo.ca to tour the Universe together.

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