Constellation of the Month: Cassiopeia

David Baumgartner writes about Cassiopeia and what to look for in December.

This article was contributed by community member David Baumgartner as part of a local series on astronomy.

Cassiopeia is one of the groups of stars known to many people. It comes in fourth in popularity after the Big Dipper, Orion, and the Pleiades.

The reason is its easily recognizable shape: like the letter W. People have been known to argue about whether it is a W or an M! Of course it depends on which way you are facing, and which position it is in as it revolves around the Pole Star. To the Greeks it was neither one, but a chair. Cassiopeia was one of the bad characters. As punishment she was tied to her throne, which was set close to the Pole of the sky. So it whirls around the Pole, and Cassiopeia has to spend half of every day upside down.

Cassiopeia and Ursa Major are the two brightest of the “circumpolar” constellations, and they whirl around opposite to each other. At times when Ursa Major is on the low side, next to the horizon, trees or low lying haze may prevent you from using its two pointer stars to find the Pole Star. So you can use Cassiopeia instead. Not as good as Ursa Major, but it will get you close. There aren’t many bright stars around that area with Polaris so it should be easy to find.

If you look at Cassiopeia when in its W shape, you will see five main stars. Counting from left to right, use the number three and four stars to draw an imaginary line to help locate Polaris. And just to make it a little harder, when it is in the M shape, I guess you could use stars number two and three to find your Pole Star.

Let’s see what December skies bring us for viewing. I always enjoy the rain, so I have a tendency to wish for rain in the daytime and clear skies at night. Although I don’t seem to have any control over this timing.

I whish you all Season Greetings, and for the best evening skies ever.

December Sky Watch

Dec 18: Last Quarter Moon occurs at 8:57 p.m.

Dec 18: Moon is at perigee (230,072 miles from Earth) 12:25 p.m.

Dec 21: Winter Solstice for the Northern Hemisphere begins at 8:19 p.m. Shortest day of the year.

Dec 22: Moon passes 4° north of Mars, 6 p.m.

Dec 22: Ursid meteor shower peaks

Dec 25: New Moon occurs at 9:13 p.m.

Dec 27: Moon passes 1.2° south of Saturn

Dec 27: Moon passes 0.6° south of Pluto at 7 a.m.

Dec 28: Moon passes 1.0° south of Venus at 6 p.m.

Dec 31: Moon passes 4° south of Neptune 1 p.m.


David Baumgartner

I am a local fella. Local schools from Fremont, Sacred Heart, Santa Anita, Hollister High, to San Benito Jr. College (Now Gavilan). Then joined the US Air Force where I specialized in Airborne Radar. Married my high school sweetheart JoAnne., shortly after three children arrived; Cindi, Michael, and Lisa. Somehow we ended up with nine Grandchildren.  Went on to San Luis Obispo, Questa, Colleges, and on to Univ. of New Mexico. Came back to Hollister. Opened up Three Pet Stores; Dave's Aquarium Pets & Supplies in SLO, Watsonville, and Hollister. The family spent two and a half years running a ranch up in Oregon. Made our way back to Hollister.  Got my Real Estate License in 1982, opened my own office in 93'. In the mean time raised Swans and revitalized my old hobby of Astronomy.  In 2001 I was named Chamber of Commence Man of the Year. I think I was the only one nominated. I don't care, I'm taking it. In December of 2018 I retired. Not sure if I was forced out or not. None the less, I am retired and I think it was time. Now the last thing I have to do is buy a coffin. I hear COSCO sells them now. But the only drawback is; you have to buy them in lots of six.  I guess I could buy them for the whole family. Not that funny, but thrifty.