Summer is Still Alive in the December Night Sky!
Even though December is upon us we still have some summer constellations residing in the western skies. Just like professional sports seasons, there’s a lot of overlap with the constellation seasons. In fact, something called the “Summer Triangle” is still hanging in there in the western heavens.
The Summer Triangle itself is not a constellation, but is made up of three bright stars from three separate constellations. They’re the brightest stars in the western sky and each is the brightest in their respective constellations. Deneb, the highest star in the west, is the brightest shiner in the constellation Cygnus the Swan. Within the stars of Cygnus is the famous and easy to see “Northern Cross” with Deneb at the top of the cross and the dimmer star Albireo at the foot. To make the cross into a swan, picture Deneb at the tail of the celestial swan and Alberio at the head. Then look for fainter stars beyond and above both ends of the crosspiece. The fainter stars, together with the three crosspiece stars, form an arc that makes up the wingspan of the swan. You can’t help but notice that Cygnus the Swan appears to be making a swan dive toward the western horizon. That seems appropriate, since Cygnus will begin to disappear from the evening sky before the end of this month, setting before evening twilight as the Earth in its orbit turns away from the big heavenly bird.
In the southwestern sky is the Great Square of Pegasus, the torso of Pegasus the Winged Horse. Just to the northeast of the Square is the constellation Andromeda the Princess, with the Andromeda Galaxy just above the Princess. The Andromeda Galaxy is the next door neighbor to our Milky Way Galaxy. Our galactic neighbor isn’t very close, though, at well over two million light years away, with just one light year equaling nearly six trillion miles. Despite that distance, you can just see the Andromeda Galaxy with the naked eye in the dark countryside as a fuzzy faint patch of light.
Gazing in the east after evening twilight, you’ll be bombarded with all kinds of bright stars and constellations, especially later in the evening. You are witnessing the rising of the winter constellations, the best of the year in my opinion. The constellations Auriga the Chariot Driver and Taurus the Bull lead the charge. Just above Taurus is the best star cluster in the sky, known both as the Pleiades and the Seven Little Sisters. This is a young group of stars, 410 light years away, that looks like a tiny Big Dipper. After 8pm Orion the Hunter, the great centerpiece of the winter constellations, takes to the low eastern sky. The three stars in a row that make the belt of the great hunter will definitely jump out at you.
We have two planets visible this month in the very low south-southwest sky very early in the evening, Venus and Mars. Venus is much brighter than Mars but you have to look for it in the extremely low southwestern sky very shortly after sunset. You won't see it for long, though, because it slips below the horizon by around 6:30.
Mars starts out the early evening a little higher in the southwestern sky, and even though it's a lot farther from Earth than it was earlier this year it has a distinct reddish glow. Forget about checking either planet with your telescope. They'll both show up really fuzzy because of the blurring effects of our atmosphere that's extremely thick along the horizon. Besides that, Venus is completely covered by a very bright poisonous cloud with acid rain drops in it!
Tonight we'll have a special treat as Mars and the new crescent moon will be in a really tight and delightful celestial hug. Look for Mars just to the upper left of the moon.
Enjoy our holiday season night skies!
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul, and is author of the book, “Stars, a Month by Month Tour of the Constellations” published by Adventure Publications. Available at bookstores and online at www.adventurepublications.net.
If you have any astronomical questions or want me to write about something you’re seeing in the night sky drop me a line at firstname.lastname@example.org