December sky

Looking southeast, 6 p.m. on Christmas Eve.

December is here, the last month of the year, and it brings us Christmas and the winter solstice.

Clear nights are rare, but when they are clear darkness comes early—and there are always interesting things to see in the evening sky. Just bundle up!

In November, I had the chance to visit the Goldendale Observatory during the “soft opening” of their remodeled facility. While not everything is quite finished, the roomy theater, displays and presentations were great.

We were lucky enough to have skies clear enough to view the Moon through the telescope as well.

The soft opening continues during the weekend after Christmas, Dec. 27 to 29, with Solar shows from 2 to 4 p.m. evening shows from  6 to 9 p.m.

Other than that, the facility is closed in December.

Regular operations at the observatory are expected to resume in January.

I recommend checking the web page at www.goldendaleobservatory.com to confirm status before you go.

The winter solstice and the start of winter comes on Sunday, Dec. 22 this year. On that day the Sun is lowest in the sky, about 21 degrees above the horizon at noon. If you were at the Tropic of Capricorn in the Southern Hemisphere, the Sun would be directly overhead.

We will have about eight hours and 38 minutes of daylight.

The bright planets Jupiter and Saturn are fading from view in December, but are still above the southwestern horizon at sunset. This month they will be joined by Venus. On Sunday, Dec. 1, look low in the southwest at 5 p.m.; you will find Jupiter low on the horizon, Venus higher in the sky to its left and Saturn to the left of Venus. Even further to the left, almost due south, will lie the crescent Moon. It should make for a nice lineup!

Venus will get higher in the sky as the month progresses, growing closer to Saturn night by night. On Tuesday, Dec. 10, Venus will be just below Saturn, and by Friday Dec. 20 it will be well to the left of Saturn, and higher in the sky. It is always interesting to watch the apparent movement of the planets in the sky as they circle the Sun. It is easy to see why the word “planet” was derived from the Greek for “wanderer.” The planets appear to wander across the sky, rather than being in seemingly fixed locations like the stars.

Our Moon will be full on Thursday, Dec. 12, with new Moon on Thursday Dec. 26. The nearly full Moon will lie just below the Pleiades star cluster on Tuesday, Dec. 10.

Early December will provide a good opportunity to see the International Space Station fly overhead. The best nights are Thursday, Dec 5, starting at about 5:56 p.m., Saturday, Dec. 7 at about 5:55 p.m., and Sunday, Dec. 8, at about 5:07 p.m. These are some of the times when the ISS will be high overhead. There are other passes too; check out heavens-above.com for those times. Enter your location in the program, and look for “ISS” under “Satellites.”

A couple of small constellations, Triangulum and Aries, are high in the east in December, above the dazzling Pleiades star cluster. Triangulum, as the name suggests, can be seen as a triangle, formed by its three brightest stars. Look for it about 25 degrees above the Pleiades, a bit to the right. (25 degrees is about the width of your spread-out hand, held at arm’s length.) Triangulum is best known as the location of a nearby galaxy, the Triangulum galaxy, about 2.7 million light-years distant. As galaxies go, it is one of our neighbors.

If you locate Triangulum, look just below it to find Aries, the ram, as a line of several relatively dim stars. Aries is one of the 12 Zodiac constellations, the ones that the Sun passes through during the year. A couple of thousand years ago, the Sun was in Aries when spring began, the vernal equinox. Today, the Sun is in neighboring Pisces at that time. This is because as the Earth rotates, it wobbles slightly, taking about 26,000 years to complete one wobble. (a phenomenon called Precession.) That causes the Earth’s polar axis to be pointed to a different place in the sky over time.

Use the picture with this article to locate this small constellations. Check them out while you are watching for Santa Claus!

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