StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

DECEMBER 2015

DECEMBER STAR MAP | MOON PHASE CALENDAR | STARWATCH INDEX | NIGHT SKY NOTEBOOK

Print Large Sky Charts For 9 p.m. EST: NORTH | EAST | SOUTH | WEST | ZENITH

Current Solar X-rays:

Current Geomagnetic Field:

1007 DECEMBER 6, 2015: Geminid Meteors: A Good Bet: Sunday and Monday mornings, December 13-14, is when Geminid meteors should be peaking at their maximum rates. Geminid activity has been on the rise since the shower’s discovery in 1862 because the orbit of the debris which produces its meteors has been shifting ever closer to Earth. Jupiter’s strong gravitational pull is responsible. In 1877 rates of 17 meteors per hour were being witnessed, 27 meteors each hour by the nineteenth century’s end. During the late twentieth century rates climbed to over 80 events per hour, and currently, they are about two meteors per minute, half from suburbia. When I was a teen growing up in the 60’s beginning my astronomical journey, the Geminids were a major event, but they still paled in contrast to the August Perseids. Now they surpass Perseid activity, but are still less observed because of the cold and often cloudy conditions which prevail in mid-December. Geminids, however, are your best bet for observing meteor activity if the weather does cooperate. They are also the only shower related to an asteroid. In 1983, 3200 Phaethon was discovered, and its orbit was quickly connected to the annual Geminid event. This gave credence to the belief that many short period comets actually end their active days masquerading as small minor planets. For North America, meteor activity should remain constant Dec. 13 and 14, but brighter meteors are expected on the 14th. You can start observing as early as 10 p.m. Face east, but observe near the darker zenith. Geminids will be diverging upward from the east. By 2 a.m. face south, but continue to look towards the zenith where the sky is darkest. Geminids will appear to radiate from an area near the bright star, Castor. A map is included with this StarWatch. View a day earlier or later if weather conditions will be inclement on maximum nights, but expect to see fainter meteors before maximum and brighter meteors afterwards. Beyond the mornings of highest activity, rates decrease rapidly.

1008 DECEMBER 13, 2015: A Telescope Under the Tree: After 6-1/2 decades of sentient life, I am still trying to understand the reasoning behind why so many people put telescopes under their trees at Christmas. I received my first spyglass refractor on my 10th birthday, and when as an early teen, I desperately wanted a weather station for the Holidays, I got a large wall mirror instead. The mirror was such a huge disappointment that it may have even solidified my decision to become an astronomer, but the mirror certainly had its perks when I began to date. If buying a telescope this Christmas is truly your heart’s desire, kindly consider these few recommendations. Stay away from Kmart, Walmart, or any department store sold telescopes. They are useless, overpriced, poorly constructed, and will do more to turn you and your children off to the pleasures of astronomy than promote its attributes. I will say that Galileo would have been proud to own a Kmart special because his instruments were even worse optically. Also consider a reflecting telescope, one that uses mirrors to bring the light that it collects to a focus rather than a refractor, which uses lenses to achieve the same purpose. Newtonian reflectors on Dobsonian mounts represent your biggest bang for the buck, but still expect to pay from $200-$500 for a decent telescope with at least two eyepieces. So where do you go to purchase a telescope? If you are a beginner, I would strongly suggest Orion at www.telescope.com. You can chat online with a representative or give them a call at 1-800-447-1001 to discuss your wishes. If you live in southeastern PA, make sure to visit Skies Unlimited, www.skiesunlimited.com, located at 52 Glocker Way, Pottstown, 19465, 1-888-947-2673. I guarantee that owner Bob Black, (who has a shopping day named after him) and his staff of Ted, Dave, and Tom will get you started in the correct direction by dispensing lots of advice with no pressure to purchase. Happy Holidays!

1009 DECEMBER 20, 2015: Old Friends Coming to Call: When I taught astronomy in the public schools, I often referred to the sky as the first TV set. There was an informational aspect to its programming as astronomer priests looked to the heavens and the motions of its wanderers, the sun, the moon, and the five known planets as portents to the destiny of civilizations and individual souls. This evolved into the pseudoscience of astrology, but there was also an entertainment quality that encompassed the starry vault. The men, women, and beasts who formed the constellations, symbolized the actors, and their positioning to one another created the stories that portrayed the dramas that unfolded during the course of a year. Yes, the programming only worked at night, and yes, after a year’s worth of time, the reruns started all over again, continuing on a regular basis to this very day. Just like I am anticipating the new Star Wars episode, The Force Awakens, the same applies to the expectancy of saying hello to the winter constellations, old friends that are now coming to call. Orion the Hunter, Taurus the Bull, Auriga the Charioteer, Canis Major and Minor (big and little dogs), Lepus the Hare (I have three rabbits as pets), and of course, my birth sign of Gemini the Twins, are now playing earlier and earlier each night. By 10 p.m., even from an urban locale, you’ll catch Orion’s, Mintaka, Alnilam, and Alnitak girding his loins in the SE about mid-sky. Slide down the belt stars of the Hunter, and you’ll arrive at the brightest luminary of the night, Sirius, the Dog Star, the nose of Canis Major the Big Dog. The only star brighter in the heavens is our sun. Rocket upward from the belt, and you’ll pass near the orangey, giant star, Aldebaran, the eye of Taurus the Bull. Orion and Taurus are not exactly on friendly terms, and their location is just one of many conflicted areas in the heavens. It’s really not that much different from our planet, except that we have the power within our humanity to change. Peace on Earth! Goodwill to all!

1010 DECEMBER 27, 2015: The Young and the Restless: Check out Orion the Hunter who is riding mid-sky, due south, at 10 p.m. this week. It is the classic winter constellation. Two bright stars, red supergiant Betelgeuse (left) and blue Bellatrix create his shoulders; three tightly grouped stars, Mintaka, Alnilam, and Alnitak form his belt; and two stars representing his knees, Saiph (left) and the blue supergiant Rigel (right), complete the pattern. Beneath Orion’s belt are three fainter, starlike objects that shape his sword. They are really star clusters in themselves, with one of the best star-forming regions in the cosmos lying at its center, the Orion Nebula. Here, some of the newest stars in our galaxy reside. These hot luminaries blast the nebula with high intensity ultraviolet light, causing the gases to glow, billow, and swirl. In the process, the gases and dust are tumbled and compressed to create new stars, sculpted by the light itself. Even at 1500 light years distant, the Orion Nebula shines with a strength that allows it to be seen as a fuzzy, extended object viewed with the unaided eye; but that’s not all. One of the most interesting hypotheses about the Orion area is that its two supergiant stars, Betelgeuse and Rigel, may be escapees, gravitational castaways that were catapulted from the Orion Nebula millions of years ago. Even the belt stars outline a loose grouping of O and B-type luminaries. These are the brightest and most massive (heaviest) stars that our galaxy has to offer. They light up the bluish arms of spiral and irregular galaxies, “burning” at luminosities of up to one million times the energy output of the sun. High mass stars shine brightly, but briefly, ending their lives in titanic stellar detonations called supernovas which enrich the galaxy with the heavier elements that can eventually generate life. Looking at Orion is like watching a soap opera, with all of its twists and turns, unfolding right in front of your very eyes in your very neighborhood. Go outside on a clear evening, look up, and behold Orion!

[December Star Map]

[December Moon Phase Calendar]