Did you know you can check out telescopes at the Library?
Thanks to a generous donation from the Louisville Astronomical Society, LFPL is excited to offer telescopes for check out at the Southwest and South Central Regional libraries. The lending period is for one week and is limited to Louisville Free Public Library cardholders in good standing, 18 years or older.
For more information on the telescope lending program, visit:
- Northeast Regional Library - (502) 394-0379
- Southwest Regional Library - (502) 933-0029
- South Central Regional Library - (502) 964-3515
December in the Sky
By Frank Nelson, Sidewalk Astronomy Coordinator for the Louisville Astronomical Society.
Happy December! The nights are long and dark, the air is cold, and the longest night of the year is nearly upon us! Next month we will all ohh and ahh over Orion and the various objects to see there, but for November I want to focus on Taurus.
Look to the east, away from the sunset, as the sky gets darker. In the middle of the month, Orion will be on the horizon. Most people will recognize the constellation of Orion and its belt. Just above Orion is the constellation Taurus the Bull. Higher still, and to the north is Perseus, which we visited the last few months.
Next to the word “Taurus” is a triangle of stars forming the head and face of the bull. The very bright star Aldebaran, visible even from the city’s light pollution, represents one of the bull’s eyes. This triangle is a star cluster named the Hyades, the closest star cluster to earth at 150 light years away. Aldebaran is not a part of the Hyades, it is only 65 light years away. Aldebaran also has at least one planet around it! This area of sky is a great target for binoculars. While you are in the area, don’t forget to view the Pleiades with binoculars or the lowest magnification your telescope has to offer. The Pleiades are 440 light years away. On this map, each of the named deep-sky objects are Messier objects. Charles Messier was a comet hunter from France active in the 1750s to 1780s. He discovered at least thirteen comets, but his list of “not comets” is how we remember him. Messier 1, the Crab Nebula, is easy to find not far from Aldebaran. And there are a few little gems in the area worth a look.
Zooming in on the bright red star Aldebaran, on a clear night the “V” will point toward two bright stars that form the end of the “horns” of the bull. The brighter of the stars at the end of the horns is Elnath, the 28th brightest star in the night sky. We are interested in the star Tianguan, Zeta Tauri. Aim you telescope at this star, at the end of the “horn” of Taurus radiating from Aldebaran. Tianguan is a blue-white giant star roughly 440 light years away, about the same distance as the Pleiades. From my house in the suburbs, I can see this star most clear nights when the moon is not nearby. Now, we get to starhop.
Center Tianguan in your finder scope. If you do not have a finder scope, use the lowest magnification eyepiece you own. If you have a 32mm eyepiece, use that one. You are going to move the telescope slightly to the west, away from the eastern horizon. Remember that the view in your telescope will be reversed. Moving slightly west, there will be a line of stars; two brighter stars on the end of the line, two fainter in the middle. If you can see both the stars in the middle, you should be able to see M1. Curve to the west-north-west and there will be a single lone star. Curve more north than west and you should see a faint, fuzzy, out of focus star. Now, increase your magnification. At about 100x power this fuzzy spot of light will look oval; on a really dark night with no moon, the patch of light will have spots of light and dark and detail that will barely be visible. Take your time and look at the object, reminding yourself that this is a star that exploded and was visible in 1054.
Now for a special treat. Most stars will look white or colorless to most people. This is due to the way the human eye processes color. Stars that have color tend to stick out and are worth viewing. Not too far from Tianguan, is one of the reddest stars in the night sky, in a field of blue stars. Go back to Tianguan and use your lowest power eyepiece or finder scope. Center the star in the eyepiece. Moving in the opposite direction we went for M1, find a tight, fainter, double to the south of Tianguan. Keep moving in the same direction and you will slide towards a pair of double stars. The eastern double is part of a line of stars pointing back towards Tianguan. Keep moving in the same direction about the same distance, roughly a degree. You will see a star labeled 120 Tauri. This is a good, easy triple star; the star in the center is much brighter than its companions. With more magnification the three stars are easy to split even on an average night. Now, go slightly west. A very red point of light will drift into view. This is The Ruby Star, a red supergiant star some 1800 light years away! Take some time and look around the area as there are other red and blue-ish stars in the area. The Ruby Star is one of my favorites.
Finally, let’s talk about the planets. Jupiter and Saturn dominated the sky over the summer. In December, they get closer and closer to the sun in the sky; by the end of the year the only bright planet visible at sunset will be Venus. Venus is the third brightest natural object in the sky and will be the first “star” visible at sunset for the next few months. Point a telescope at that “star,” increase the magnification and watch as Venus’ shape changes over the next three months. Venus has phases just like the moon does! For those wanting to look at Mars, 2020 is going to be your year. Mars will be directly opposite the sun in October, much higher above the horizon than it was 2018. On December 22-23, the moon will slide by Mars. Look at the spot on the horizon where the sun is starting to rise. Just above that point will be a bright red “star” that does not twinkle. This is Mars. If you are a morning person, watch Mars get higher above the horizon every night as the year progresses. Also to note will be a close pass of the moon and Venus on December 28. Look at the western horizon as the sun is setting. Venus will shine about 2° above a very new moon. The next night, the moon will be some 10° above Venus. These conjunctions are pretty and worthy of photography!
For star charts, planet positions and telescope targets for the month of December, please visit the Astro League website. The images in this article are screen captures from the free program Stellarium. Want to learn how to use Stellarium? Come out to our general meeting, or our public observation events listed on our website. The LAS, along with the Gheen Planetarium, will host the last public viewing and monthly Planetarium show of the 2010’s on December 13. LAS members will be available to answer telescope purchasing questions, space questions, and weather permitting, telescopes showing the moon, Saturn and Venus will be in the parking lot! And our last event of the year, our annual Christmas party, will be Saturday December 14 in Tom Sawyer park. See our website https://louisville-astro.org/events for details and directions.