THE OBSERVER Newsletter of The Tri-State Astronomers December 2020 Volume 35 Number 12 MONTH AT A GLANCE The next TSA Virtual Meeting December 16, 7:00 PM This is the final monthly edition of the OBSERVER. The OBSERVER has been published for 35 years since November 1985. ©BlueMarmot / CalculatorCat.Com There are plans to publish a special remembrance edition after the Last Quarter Mon Dec 07 first of the year. Please submit any suggestions you have for the OBSERVER Remembrance Edition by January 15. New Moon Star Party (Club Members Only) Fri Dec 11 or Sat Dec 12, Dusk Geminids Peak Mon Dec 14, 2:00 AM Gemini New Moon Mon Dec 14 TSA Virtual Meeting Wed Dec 16, 7:00 PM Virtual Meeting Jupiter/Saturn conjunction 0°6 This is their closest in 397 years. Next closest will be in 2080 Mon Dec 21, 4:50 PM - 6:55 PM Winter Solstace Mon Dec 21, 5:02 AM First Quarter Mon Dec 21 Full Moon Tue Dec 29 TristateAstronomers.org December Sky Map Early December 7:00 PM - Late December 6:00 PM 2 Our Friendly Skies By Alicia Kutzner Robertson, WCPS STEM/Planetarium Resource Teacher And Andy Smetzer, Tristate Astronomers THE DECEMBER SKY December is the season of celebration! Whether you celebrate Hanukkah, Christmas, Kwanzaa, Boxing Day or Omisoka, this is a time of year that we look forward to as it means family and friends will gather together, if only virtually, to enjoy each other’s company. What better way to spend time together than looking at the stars with a great big cup of cocoa! After all, no matter where your family is you are all going to be looking at the same sky! THE DECEMBER STARS This has always been my favorite time of year as it means that my friend, the constellation Orion, will be hunting the skies for an- other season. Orion is part of the Winter Circle or Winter Hexagon, an asterism that is made up of stars from 6 different constel- lations. Orion is easily identified by first locating the three stars that make up his belt. From the lowest star on his belt, move up to the bright star, Betelgeuse, which is located in Orion’s armpit. Betelgeuse is a red supergiant that will eventually go supernova, leaving Orion arm pitless! However, it is not Betelgeuse that we will use to make our way clockwise around the Winter Circle but Rigel, which can be found down and to the west of the highest star in Orion’s belt. Traveling down and to the east of Rigel, you will find the bright star Sirius, the nose of Orion’s hunting dog in the constellation Canis Major. For the month of December, I prefer to believe it is the nose of a reindeer that Orion uses to carry his hunting equipment - similar to another jolly man that we know! Of course, both Orion and Canis Major are accompanied by the con- stellation Canis Minor, Orion’s small hunting dog. You can find him by looking up and east of Sirius to the bright star Procyon. From Procyon, head straight up and you will see two stars stacked one almost directly above the other. These stars, Pollux and Castor, are the brightest stars in the constellation Gemini. Watch out for the twins on December 2 as Castor tries to punt the moon across the sky! Continue looking up and to the west you will find the star Capella, located at the top of the Winter Circle. Capella is the brightest star in the constellation Auriga, the Charioteer. Although Capella appears to be one star, if you had a telescope strong enough to see it well, you would notice it is actually 4 stars arranged in 2 binary star systems. The stars in each system appear to dance a slow waltz around one another, having chosen their partner long ago. Continue clockwise and down to the great red eye of Taurus the Bull, our final constellation in the Winter Circle. At first glance, the eye, Aldebaran, may seem to be the same size as any other star. In actuality, Aldebaran is approximately 44 times larger than our own Sun, not a star to be trifled with! THE DECEMBER SOLAR SYSTEM Just as December heralds the end of the year, it also brings us to the end of a spectacular season of planet watching, including one final show! Before we begin talking about planets, there are a few notes I would like you to keep in mind. As we discuss the visibility of planets from Earth, we talk in terms of their apparent magnitude or how bright objects in space appear to us as we view them from Earth. On the apparent magnitude scale, the lower the apparent magnitude, the brighter the object appears to be. Also, viewing notes are made assuming you are observing over a flat horizon from Hagerstown, MD. However, you may be viewing the skies from a different location and/or mountains, trees and buildings may obstruct your view of the horizon. Both of those factors can affect when the object rises and sets and how visible it is from where you are. Morning Planets 3 MERCURY is closing out the year as fickle as ever. He will start the month visible in the morning, rising at 6:22 am and end the month visible in the evening, setting at 5:20 pm. Mercury also has a hard time deciding which constellation to settle down in and travels quickly from one constellation to another this month. He starts December in Libra, but travels through Scorpio and Ophiuchus to end the month in Sagittarius on December 19, shining more brightly then he did at the beginning of the month with a magnitude of -1. VENUS remains a bit more steady throughout the month, rising before sunrise and setting at approximately 3:25 pm each day, shining with an apparent magnitude of approximately -4. Just like Mercury, she too tends to wander this month, moving from Libra into Scorpio over the evening of the 17th and ending the month in Ophiuchus on the 22nd. Evening Planets JUPITER and SATURN continue their friendship in the early evening December skies. Jupiter rises at 10:32 am on Dec. 1 and sets at 8:07 pm at the beginning of the month, but rises earlier and earlier throughout the month until he is rising at 8:56 am and setting at 6:41 pm on the 31st. He remains the jewel of the sky, shining with a magnitude averaging -2 throughout the month and travels from the constellation of Sagittarius into Capricorn over the night of the 16th. Not one to be left alone, SATURN rises and sets just minutes behind Jupiter throughout the month as she strives to catch up to Jupiter, even moving from the constellation of Sagittarius into Capricorn on the same evening as Jupiter. However, the ever shy Saturn still allows Jupiter to be the star of the friendship, shining with a lesser average magnitude of 1. SPECIAL EVENTS This is a month filled with celestial events to celebrate. From the 10th to the 12th, Venus and the moon will rise together at sunrise, being closest together on the 12th. This will be a great time to look at the dark side of the moon as it is illuminated by earthshine or sunlight that is reflected from Earth to the moon and back again. The Geminids meteor shower will emanate from the constellation of Gemini on the 13th and 14th. For the best viewing, head out around 2:00 am on Dec. 14. During the peak of the shower, you may be able to see 50 - 100 meteors per hour! And, lucky for us, the Geminids coincide with the new moon, so you will not have to worry about moonlight obscuring your view of the shower. The Winter Solstice occurs on Monday, Dec. 21 at 5:02 am. The Winter Solstice marks the shortest day of the year in the north- ern hemisphere when the sun is directly over the Tropic of Capricorn in the southern hemisphere and everything above the Arctic Circle spends the day in darkness. Celebrate by building a yule altar to honor the return of the sun with a gold, silver or yellow candle surrounded by evergreens and pinecones! The 21st will also see the great conjunction of those friendly planets Jupiter and Saturn. Conjunction happens when 2 or more objects meet up in the sky. This conjunction is called a “great” conjunction as Jupiter and Saturn are the largest planets in our solar system. At their closest, Jupiter and Saturn will only be .1 degree apart, which is the diameter of the moon and is a much smaller distance than the width of your little finger when your hand is held at arm’s length. Jupiter and Saturn will be so close that they may appear as one very bright star. However, don’t delay your observing of this great conjunction! Jupiter and Saturn will be visible at sunset, 4:50 pm, but they will set at 6:55 pm. Blink and you may miss the conjunction, which would be unfortu- nate as this is the first great conjunction since 2000, the closest since 1623 and won’t be matched until March 15, 2080. On December 23, the moon is just below Mars with Uranus trailing Mars to the SE. On December 24, however, the moon will be directly below Uranus with Mars directly to the West.