StarWatch: Moravian College Astronomy

JANUARY 2013

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

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Geminid Radiant: Note how the four meteors captured in this composite digital image seem to be diverging from a vanishing point just to the left of the top star of the two bright stars in the very lower left of the picture. The two bright stars are Castor and Pollux of the Gemini Twins. At least three of the four meteors are Geminids. The non-Geminid meteor may be the shooting star near the center left of the picture. The bright star nearest to the faintest meteor is really the planet Jupiter. Composite image taken between midnight and 2:30 a.m., December 14 from Shooting Star Farm near Pleasant Valley, PA...

855 JANUARY 6, 2013: Surprises Could Make 2013 Interesting: After a dream year like 2012, where a major US solar eclipse, a transit of Venus, many great meteor showers with little or no intrusion from moonlight, and beautiful planetary gatherings graced the calendar, can there be any improvement? The truthful answer is probably no, unless there are some surprises. One of them could possibly be related to sunspot activity which is edging towards maximum during 2013. A bespectacled sun means it is more magnetically active and more likely to produce increased flare activity and coronal mass ejections. All of these can send charged particles—electrons, protons, and the nuclei of helium atoms screaming towards the Earth, some to be funneled into Earth’s magnetosphere to create the colorful, whimsical curtains of light we call auroras. For unknown reasons the fall produces the best displays of northern lights. You can sign up for space weather alerts at www.spaceweather.com. Another big surprise could come from comet C/2012 S1 (ISON), a sungrazer set to round Sol at a scant 1.1 million miles on November 28. If the comet survives perihelion, it could produce a magnificently long tail perpendicular to the horizon as it ascends higher and higher into the dawn sky during the first two weeks of December. Its survival at that close range sun is the big “if.” In addition, Comet PANSTARRS, C/2011 L4 should become an easy binocular target low to the horizon in the west after sunset during mid-March. Also the very predictable Perseid meteor shower, which rarely disappoints, reaches maximum activity on the morning of August 13. The moon sets around 11 p.m. the previous night. During the winter months Jupiter dominates the evening sky, followed by Saturn in the spring, and Venus, low in the west after sunset during the summer and fall. The year 2013 may seem dull on the surface, but then watch out for those big surprises.

856 JANUARY 13, 2013: Skinny Moon Debuts in Evening Sky: Have you noticed the sun setting just a tad bit later? December 7 was the earliest sunset, 4:35 p.m., for souls living at 40 degrees north latitude. We still haven’t gained that much daylight since the winter solstice, the shortest day of the year, but we are at least making the most progress at the correct time of the day—evening. Sunsets are now about 25 minutes later. Sunrises, on the other hand, are only three minutes earlier in comparison to the latest sunrise which occurred on January 4. The bottom line is that we still have a long way to go before spring, even though I remain optimistic. At the beginning of the week, you’ll notice a scimitar-shaped waxing crescent moon hugging the SW horizon about 45 minutes after sundown. The horseshoe shape of the moon always points to the location of the sun below the horizon, while the tilt of the horseshoe gives a good approximation of the tilt of the moon’s orbital plane to the horizon. Bring binoculars along to help accent one of the most beautiful aspects of a young moon, earthshine. When the moon is near its new phase, the Earth as viewed from the moon is nearly full. The Earth consumes 16 times the sky area of a full moon and reflects light about five times more efficiently than the moon, making Earth appear about 80 times brighter (5 x 16 = 80) in the moon’s sky than a full moon appears in our sky. Light reflected from a nearly full Earth is reflected back to us by the moon, producing sufficient illumination on the dark face of the moon to allow the entire disk to be seen. This ashen light, earthshine, is also referred to as “the old moon in the new moon’s arms.” Although Sunday through Tuesday will be the best time to catch the ashen light with the unaided eye, binoculars will still reveal its presence right through First Quarter (Friday) if conditions are clear enough. More fun lunar observations next week or read ahead at www.astronomy.org...

A six day old moon... Gary A. Becker image using a 3.5-inch Questar...

857 JANUARY 20, 2013: Read by Moonlight: I used to hate when the full moon dominated the night sky. Its light hid the stars, nebulae, and clusters—all of the “beautiful” objects that I wanted to observe with a new telescope that I had spent about two years constructing. I was 18 at the time. Moonlight was also the ban of meteor observing, the avenue through which I became involved in astronomy. A bright moon, even against a very transparent sky, decreases shooting star rates by about 75 percent. Fortunately, age has tempered my stance against moonlight, and that’s good thing. Let’s face it; half of our lives are spent under the influence of a bright moon, so why not simply submit, enjoy, as well as make use of its light. Several images taken under the influence of Luna are posted with the online version of this article at www.astronomy.org. When my grandfather, Ewald Marcus, was a soldier in WW1 fighting for the Germans on the Russian front, he often read the newspaper at the end of the day by the light of a bright moon. Yes, he always mentioned that there was a snowpack on the ground, but that is not a prerequisite for a successful read. What most people fail to realize is that it takes time for the eye to dark adapt to the moon’s subdued lighting, five to 10 minutes depending upon your age, with older people taking longer. The other consideration is to find a location which is away from direct or indirect exterior lighting, except for the moon. You’ll have plenty of time to conduct this experiment, because as the week unfolds, the moon continues to brighten as it grows through its gibbous phase, where both sides appear to be bulbous in shape. A very bright star will appear to trail the moon on Sunday. That’s Jupiter! On Monday (1/21), the moon approaches Jupiter to within a degree, a beautiful sight with or without binoculars. The moon reaches its full phase late on the evening of the 26th.; Silence of the Lambs:
Hello Gary from over here in the (Moravian College) Language Department! I don´t always have time to read your missives, but I enjoy them when I do. This one, “Read by Moonlight,” reminded me of when I became aware of the special qualities of this light. Backpacking in the mountains of northern Spain in 1978, my husband and I stayed under a roof one night at a shelter. Taking a walk on the hill behind the shelter, we turned to look at a massive mountain a mile or less distant, seen across a shallow green saucer-shaped landscape. The full moon was behind us and the view of the mountainside took our breath away. You could see every crack and crevice on the surface. We contemplated the scene in silence for a time, then noticed that several yards from us lay an assortment of white rocks. My husband said, "In the moonlight those rocks look almost like a flock of sheep!" Then one of them said, "Baaaa".
Thanks for the interlude! Maggie (Margaret L. Snyder)

858 JANUARY 27, 2013: The Groundhog Speaks: A marvelous little celebration occurs on Saturday, February 2, where a feted groundhog named Punxsutawney Phil, in Punxsutawney, PA is going to predict whether winter is over or the season of cold will extend to the vernal equinox. P-Phil will speak to his top hat handler in a language known as “groundhogese,” a word absent from the dictionary, to convey his sentiments on the seasonal adjustments. If conditions are gloomy on February 2, and Phil does not see his shadow at daybreak, an early spring is at hand. If, however, the sun is shining and Phil observes his stretched silhouette, the cold will continue for another six weeks. The link between astronomy and Groundhog Day is actually straightforward. We have four major seasons occurring during a year, each separated by three months. It is no coincidence that Christmas and Easter became religious holidays near the start of two of these special times. While pagan Rome was celebrating the passing of the low sun at winter solstice and the promise of a new planting and harvesting season, the Saturnalia, early Christians masked their observance of Christ’s birth during the hoopla. Likewise, pagan festivals which celebrated the victory of light over darkness at the time of the vernal equinox were perfect for rejoicing about Christ’s victory over the darkness of death. Also important were the midpoints between the seasons known as cross-quarter days that anticipated these changes. Groundhog Day was one of them, and it is a throwback to the burrowing badgers of Europe. They could determine whether spring was at hand by examining the root structures of trees and plants. In America, groundhogs became an apt substitute. Earlier, the Celts celebrated this date when ewes started lactating as spring’s rebirth. Two other cross-quarter days significant in Western culture are May Day and Halloween. Yes, astronomy is everywhere in our traditions.